Re: want to show list of available options and arguments in my command line utility

[Peter Otten]

Santosh Kumar wrote:

> I have a script that takes an which basically takes a command line
> argument and prints after processing. If I don't give the argument to
> the script, it gives me a ValueError:
> 
> ValueError: need more than 1 value to unpack
> 
> I was trying to utilizing this space, if there is no argument I want it
> to show:
> usages: myscriptpy [option] [argument]
> 
> options:
> --help  print this help message and exit
> 
> Nothing more than that. I was looking on the argparse module, it can
> do the stuffs I want, but
> I don't to rewrite and mess up my current script. What should I do?

Learning to use the argparse module is a worthwhile endeavour. You should 
rewrite and not mess up your script. This is easier if you write unit tests 
to accompany the code doing the "real work".

Don't forget to use version control (see http://hginit.com/ for example) to 
help you back out if something goes awry.

Also note that learning to throw away suboptimal code is important, too.

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Re: want to show list of available options and arguments in my command line utility

[Steven D'Aprano]

On Sun, 16 Sep 2012 12:20:08 +0530, Santosh Kumar wrote:

> I have a script that takes an which basically takes a command line
> argument and prints after processing. If I don't give the argument to
> the script, it gives me a ValueError:
> 
> ValueError: need more than 1 value to unpack
> 
> I was trying to utilizing this space, if there is no argument I want it
> to show:
> usages: myscriptpy [option] [argument]
> 
> options:
> --help  print this help message and exit
> 
> Nothing more than that. I was looking on the argparse module, it can do
> the stuffs I want, but
> I don't to rewrite and mess up my current script. What should I do?

Then don't mess it up.


What you are basically asking for sounds like "I want to add this cool 
feature to my project, but I don't want to actually do the work of adding 
the feature. How can I snap my fingers and make it work just like magic?"

The answer is, you can't.

Either:

1) Do without the feature; or

2) Program the feature.

For number 2), you can either modify your script to use argparse to deal 
with the argument handling (which is probably simplest), or you can try 
to duplicate argparse's functionality yourself.

Make a backup copy first -- never, ever, ever work on the only copy of a 
working script. Or better still, use a proper VCS (version control 
system) to manage the software. But for small changes and simple needs, a 
good enough solution is "always edit a copy".

In this case, it *may* be simple enough to duplicate the functionality. 
There's no way to tell, because you don't show any code, but my *guess* 
is that you have a line like:

a, b = sys.argv

and if you don't provide any command-line arguments, that fails with 

ValueError: need more than 1 value to unpack

(Lots and lots and lots of other things will also fail with the same 
error.)

Is this case, the fix is simple:

args = sys.argv[1:]  # ignore the first entry, which is unimportant
if len(args) == 1:
arg = args[0]
process(arg, default_option)
elif len(args) == 2:
option, arg == args
process(arg, option)
elif len(args) > 2:
do_error('too many arguments')
else:
do_error('not enough arguments')

But as the argument checking code gets more extensive, it is time to just 
use argparse or one of the other libraries for argument checking instead.



-- 
Steven
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Re: want to show list of available options and arguments in my command line utility

[Steven D'Aprano]

On Sun, 16 Sep 2012 12:20:08 +0530, Santosh Kumar wrote:

> I have a script that takes an which basically takes a command line
> argument and prints after processing. If I don't give the argument to
> the script, it gives me a ValueError:
> 
> ValueError: need more than 1 value to unpack
> 
> I was trying to utilizing this space, if there is no argument I want it
> to show:
> usages: myscriptpy [option] [argument]
> 
> options:
> --help  print this help message and exit
> 
> Nothing more than that. I was looking on the argparse module, it can do
> the stuffs I want, but
> I don't to rewrite and mess up my current script. What should I do?

Then don't mess it up.


What you are basically asking for sounds like "I want to add this cool 
feature to my project, but I don't want to actually do the work of adding 
the feature. How can I snap my fingers and make it work just like magic?"

The answer is, you can't.

Either:

1) Do without the feature; or

2) Program the feature.

For number 2), you can either modify your script to use argparse to deal 
with the argument handling (which is probably simplest), or you can try 
to duplicate argparse's functionality yourself.

Make a backup copy first -- never, ever, ever work on the only copy of a 
working script. Or better still, use a proper VCS (version control 
system) to manage the software. But for small changes and simple needs, a 
good enough solution is "always edit a copy".

In this case, it *may* be simple enough to duplicate the functionality. 
There's no way to tell, because you don't show any code, but my *guess* 
is that you have a line like:

a, b = sys.argv

and if you don't provide any command-line arguments, that fails with 

ValueError: need more than 1 value to unpack

(Lots and lots and lots of other things will also fail with the same 
error.)

Is this case, the fix is simple:

args = sys.argv[1:]  # ignore the first entry, which is unimportant
if len(args) == 1:
arg = args[0]
process(arg, default_option)
elif len(args) == 2:
option, arg == args
process(arg, option)
elif len(args) > 2:
do_error('too many arguments')
else:
do_error('not enough arguments')

But as the argument checking code gets more extensive, it is time to just 
use argparse or one of the other libraries for argument checking instead.



-- 
Steven
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Re: unit test strategy

[Steven D'Aprano]

On Fri, 14 Sep 2012 19:59:29 -0700, Aaron Brady wrote:

> Hello,
> 
> I've developing a test script.  There's a lot of repetition.  I want to
> introduce a strategy for approaching it, but I don't want the program to
> be discredited because of the test script.

Test scripts should be simple enough that they don't require test scripts 
of their own. Or at least, not too many "test-the-test" tests. It is 
possible to avoid repetition without making convoluted, hard to 
understand code. Based on the tiny code fragments you give below, I 
suspect that your test script will need more testing than the code it 
tests!


> Therefore, I'd like to know
> what people's reactions to and thoughts about it are.

I'd love to make some suggestions, but I have *no idea* what you are 
talking about. See further comments below:


> The first strategy I used created an iterator and advanced it between
> each step:

What are you using an iterator for? What does this have to do with unit 
testing?

So far, your explanation is rather lacking. It's a bit like:

"I want to create an alarm system for my home, so I put in a screw and 
tightened it after each step."

Doesn't really help us understand what you are doing.


>   self.op_chain(range(5), ('add', 5))
>   self.op_chain(range(5), ('add', -2), ('add', -1))
>   self.op_chain(range(5), ('discard', -1), ('add', 5))
>   self.op_chain_ok(range(5), ('update', [0, 1]))
> Etc.

Where is the iterator you created? Where are you advancing it? What's 
op_chain do?


> I'm considering something more complicated.  'iN' creates iterator N,
> 'nN' advances iterator N, an exception calls 'assertRaises', and the
> rest are function calls.
[...]

You've proven that even in Python people can write obfuscated code.


> Do you think the 2nd version is legible?

Neither version is even close to legible.


> Could it interfere with the accuracy of the test?

Who knows? I have no clue what your code is doing, it could be doing 
*anything*.



-- 
Steven
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Re: datetime issue

[Νικόλαος Κούρας]

dn = datetime.datetime.now()
dd = datetime.timedelta(hours=2)
date = dn + dd
date = date.strftime( '%y-%m-%d %H:%M:%S' )

still giving me texas,us time for some reason
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RE: Moving folders with content

[jyoung79]

Thank you  "Nobody" and Hans!

> You may want to use the subprocess module to run 'ditto'.  If
> the destination folder does not exist, then ditto will copy MacOS
> specific aspects such as resource forks, ACLs and HFS meta-data.

This looks like a good direction to go.  Maybe something like:

>>> import os
>>> import subprocess
>>> 
>>> p1 = os.path.expanduser('~/Desktop/IN/Test/')
>>> p2 = os.path.expanduser('~/Desktop/OUT/Test/')
>>> 
>>> cmd = 'ditto -vV "' + p1 + '" "' + p2 + '"'
>>> 
>>> v = subprocess.check_output(cmd, shell=True)
>>> Copying /Users/jay/Desktop/IN/Test/ 
copying file ./.DS_Store ... 
6148 bytes for ./.DS_Store
copying file ./dude.txt ... 
4 bytes for ./dude.txt
copying file ./new.png ... 
114469 bytes for ./new.png

Jay
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Re: Python Logging: Specifying converter attribute of a log formatter in config file

[Vinay Sajip]

On Thursday, August 30, 2012 11:38:27 AM UTC+1, Radha Krishna Srimanthula wrote:
> 
> Now, how do I specify the converter attribute (time.gmtime) in the above 
> section?

Sadly, there is no way of doing this using the configuration file, other than 
having e.g. a

class UTCFormatter(logging.Formatter):
converter = time.gmtime

and then using a UTCFormatter in the configuration.

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Re: datetime issue

[Νικόλαος Κούρας]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 10:51:18 π.μ. UTC+3, ο χρήστης Νικόλαος Κούρας 
έγραψε:
> dn = datetime.datetime.now()
> 
> dd = datetime.timedelta(hours=2)
> 
> date = dn + dd
> 
> date = date.strftime( '%y-%m-%d %H:%M:%S' )
> 
> 
> 
> still giving me texas,us time for some reason

which is same as this:

date = ( datetime.datetime.now() + datetime.timedelta(hours=2) ).strftime( 
'%y-%m-%d %H:%M:%S')

this also doesnt work either:

date = ( datetime.datetime.now(hours=2).strftime( '%y-%m-%d %H:%M:%S')

if only it would!
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Re: datetime issue

[Νικόλαος Κούρας]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 8:53:57 π.μ. UTC+3, ο χρήστης Dennis Lee Bieber 
έγραψε:
> On Sat, 15 Sep 2012 22:15:38 -0700 (PDT), Íéêüëáïò Êïýñáò
> 
>  declaimed the following in
> 
> gmane.comp.python.general:
> 
> 
> 
> 
> 
> > 
> 
> > If i wanted to alter the following line, how would i write it?
> 
> > 
> 
> > date = datetime.datetime.now()+datetime.timedelta(hours=2).strftime( 
> > '%y-%m-%d %H:%M:%S')
> 
> > 
> 
> > But that doesnt work,
> 
> 
> 
>   What did you expect? Object methods bind tighter than operators so
> 
> what you have is the equivalent of
> 
> 
> 
> dn = datetime.datetime.now()
> 
> dd = datetime.timedelta(hours=2).strftime(...)
> 
> date = dn + dd
> 
> 
> 
>   Try
> 
> 
> 
> >>> import datetime
> 
> >>> date = datetime.datetime.now()+datetime.timedelta(hours=2).strftime( 
> >>> '%y-%m-%d %H:%M:%S')
> 
> Traceback (most recent call last):
> 
>   File "", line 1, in 
> 
> AttributeError: 'datetime.timedelta' object has no attribute 'strftime'
> 
> >>> date = (datetime.datetime.now()+datetime.timedelta(hours=2) ).strftime( 
> >>> '%y-%m-%d %H:%M:%S')
> 
> >>> date
> 
> '12-09-16 03:50:44'
> 
> >>> 
> 
> 
> 
>   Note the ( ) wrapping the the + clause, with strftime() applied to
> 
> the result of that...
> 
> -- 
> 
>   Wulfraed Dennis Lee Bieber AF6VN
> 
> wlfr...@ix.netcom.comHTTP://wlfraed.home.netcom.com/



date = ( datetime.datetime.now() + datetime.timedelta(hours=8) ).strftime( 
'%y-%m-%d %H:%M:%S')

but iam giving +8 hours which is the time difference between texas, us where 
the server sits and Greece's time.

cant we somehow tell it to use GMT+2 ?

also it would be nice if datetime.datetime.now(GMT+2) can be used.
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Re: datetime issue

[Steven D'Aprano]

On Sun, 16 Sep 2012 01:25:30 -0700, Νικόλαος Κούρας wrote:
[...]

You seem to be emailing python-list AND posting to comp.lang.python (or 
the gmane mirror). Please pick one, or the other, and not both, because 
the mailing list and the newsgroup are mirrors of each other. Anything 
you send to the mailing list will be mirrored on the newsgroup 
automatically, there is no need to manually duplicate the post.


Thank you.


-- 
Steven
-- 
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Re: datetime issue

[Νικόλαος Κούρας]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 12:53:42 μ.μ. UTC+3, ο χρήστης Steven D'Aprano 
έγραψε:
> On Sun, 16 Sep 2012 01:25:30 -0700, Νικόλαος Κούρας wrote:
> 
> [...]
> 
> 
> 
> You seem to be emailing python-list AND posting to comp.lang.python (or 
> 
> the gmane mirror). Please pick one, or the other, and not both, because 
> 
> the mailing list and the newsgroup are mirrors of each other. Anything 
> 
> you send to the mailing list will be mirrored on the newsgroup 
> 
> automatically, there is no need to manually duplicate the post.
> 
> 
> 
> 
> 
> Thank you.
> 
> 
> 
> 
> 
> -- 
> 
> Steven

Iam sorry i didnt do that on purpose and i dont know how this is done.

Iam positng via google groups using chrome, thats all i know.

Whats a mailing list?
Can i get responses to my mail instead of constantly check the google groups 
site?
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Re: Moving folders with content

[Hans Mulder]

On 16/09/12 10:02:09, jyoun...@kc.rr.com wrote:
> Thank you  "Nobody" and Hans!

You're welcome!

>> You may want to use the subprocess module to run 'ditto'.  If
>> the destination folder does not exist, then ditto will copy MacOS
>> specific aspects such as resource forks, ACLs and HFS meta-data.
> 
> This looks like a good direction to go.  Maybe something like:
> 
 import os
 import subprocess

 p1 = os.path.expanduser('~/Desktop/IN/Test/')
 p2 = os.path.expanduser('~/Desktop/OUT/Test/')

 cmd = 'ditto -vV "' + p1 + '" "' + p2 + '"'

 v = subprocess.check_output(cmd, shell=True)

This looks iffy: it would break if there would be any double
quotes in p1 or p2.  You might think that os.path.expanduser
would never expand '~' to something containing a double quote,
but you'd be wrong:

>>> import os
>>> os.environ['HOME'] = 'gotcha!"; rm -rf '
>>> print(os.path.expanduser('~/Desktop/IN/Test/'))
gotcha!"; rm -rf /Desktop/IN/Test/

It's easy and safer to avoid using 'shell=True' option:

cmd = ['ditto', '-vV', p1, p2]
v = subprocess.check_output(cmd, shell=False)

In this case, the safer version also happens to be shorter and
more readable.  But you should get into the habit of using
shell=False whenever possible, because it is much easier to
get it right.


Hope this helps,

-- HansM
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Re: datetime issue

[Steven D'Aprano]

On Sun, 16 Sep 2012 03:15:11 -0700, Νικόλαος Κούρας wrote:

> Whats a mailing list?
> Can i get responses to my mail instead of constantly check the google
> groups site?

http://mail.python.org/mailman/listinfo/python-list



-- 
Steven
-- 
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Re: datetime issue

[Νικόλαος Κούρας]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 1:49:38 μ.μ. UTC+3, ο χρήστης Steven D'Aprano 
έγραψε:
> On Sun, 16 Sep 2012 03:15:11 -0700, Νικόλαος Κούρας wrote:
> 
> 
> 
> > Whats a mailing list?
> 
> > Can i get responses to my mail instead of constantly check the google
> 
> > groups site?
> 
> 
> 
> http://mail.python.org/mailman/listinfo/python-list
> 
> 
> 
> 
> 
> 
> 
> -- 
> 
> Steven

Thank you, i prefer to be notifies only to thread iam initiating or answering 
to not all of te threads. Is this possible?
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Re: datetime issue

[Steven D'Aprano]

On Sun, 16 Sep 2012 03:54:45 -0700, Νικόλαος Κούρας wrote:

> Τη Κυριακή, 16 Σεπτεμβρίου 2012 1:49:38 μ.μ. UTC+3, ο χρήστης Steven
> D'Aprano έγραψε:
>> On Sun, 16 Sep 2012 03:15:11 -0700, Νικόλαος Κούρας wrote:
>> 
>> 
>> 
>> > Whats a mailing list?
>> 
>> > Can i get responses to my mail instead of constantly check the google
>> 
>> > groups site?
>> 
>> 
>> 
>> http://mail.python.org/mailman/listinfo/python-list

> Thank you, i prefer to be notifies only to thread iam initiating or
> answering to not all of te threads. Is this possible?

No. That's not how mailing lists work. Every email gets posted to all 
members, unless they go onto "No Mail", in which case they get no emails 
at all.

You are not paying anything for the help you are receiving, except to 
give your own time in return to help others. We are all volunteers here, 
and nobody is going to force you to volunteer in return, but if everyone 
only received threads that they initiated, nobody would see new threads 
and nobody would get any answers at all.



-- 
Steven
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newbie question : gedit as an ide

[Mayuresh Kathe]

new to the group, a quick hello to all.  :-)
does anyone use gedit as an 'ide' for python development?
if yes, may i know the caveats against using 'idle', 'bpython', etc?

thank you.
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Re: datetime issue

[Νικόλαος Κούρας]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 2:34:34 μ.μ. UTC+3, ο χρήστης Steven D'Aprano 
έγραψε:
> On Sun, 16 Sep 2012 03:54:45 -0700, Νικόλαος Κούρας wrote:
> 
> 
> 
> > Τη Κυριακή, 16 Σεπτεμβρίου 2012 1:49:38 μ.μ. UTC+3, ο χρήστης Steven
> 
> > D'Aprano έγραψε:
> 
> >> On Sun, 16 Sep 2012 03:15:11 -0700, Νικόλαος Κούρας wrote:
> 
> >> 
> 
> >> 
> 
> >> 
> 
> >> > Whats a mailing list?
> 
> >> 
> 
> >> > Can i get responses to my mail instead of constantly check the google
> 
> >> 
> 
> >> > groups site?
> 
> >> 
> 
> >> 
> 
> >> 
> 
> >> http://mail.python.org/mailman/listinfo/python-list
> 
> 
> 
> > Thank you, i prefer to be notifies only to thread iam initiating or
> 
> > answering to not all of te threads. Is this possible?
> 
> 
> 
> No. That's not how mailing lists work. Every email gets posted to all 
> 
> members, unless they go onto "No Mail", in which case they get no emails 
> 
> at all.
> 
> 
> 
> You are not paying anything for the help you are receiving, except to 
> 
> give your own time in return to help others. We are all volunteers here, 
> 
> and nobody is going to force you to volunteer in return, but if everyone 
> 
> only received threads that they initiated, nobody would see new threads 
> 
> and nobody would get any answers at all.
> 
> 
> 
> 
> 
> 
> 
> -- 
> 
> Steven

You are right, i will set to receive them all.

But i dont know what to do about the thing you say that i double post.

I use google groups i dont intentionally post to python-list too.

How can i avoid that and just only post to python google group?
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Re: unit test strategy

[Mark Lawrence]

On 15/09/2012 03:59, Aaron Brady wrote:

Hello,

I've developing a test script.  There's a lot of repetition.  I want to 
introduce a strategy for approaching it, but I don't want the program to be 
discredited because of the test script.  Therefore, I'd like to know what 
people's reactions to and thoughts about it are.

The first strategy I used created an iterator and advanced it between each step:
self.op_chain(range(5), ('add', 5))
self.op_chain(range(5), ('add', -2), ('add', -1))
self.op_chain(range(5), ('discard', -1), ('add', 5))
self.op_chain_ok(range(5), ('update', [0, 1]))
Etc.

I'm considering something more complicated.  'iN' creates iterator N, 'nN' 
advances iterator N, an exception calls 'assertRaises', and the rest are 
function calls.
dsi= dict.__setitem__
ddi= dict.__delitem__
dsd= dict.setdefault
KE= KeyError
IE= IterationError
self.chain(range(10), 'i0', (dsi, 0, 1), 'n0', (dsi, 10, 1), (IE, 'n0'))
self.chain(range(10), 'i0', 'n0', (dsd, 0, 0), 'n0', (dsd, 10, 1), (IE, 
'n0'))
self.chain(range(10), 'i0', (KE, ddi, 10), 'n0', (ddi, 9), (IE, 'n0'))

Do you think the 2nd version is legible?  Could it interfere with the accuracy 
of the test?



http://docs.python.org/library/unittest.html#organizing-test-code seems 
to be a good starting point for avoiding repetition and introducing a 
strategy.


--
Cheers.

Mark Lawrence.

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Obnoxious postings from Google Groups (was: datetime issue)

[Ben Finney]

Νικόλαος Κούρας  writes:

> Iam sorry i didnt do that on purpose and i dont know how this is done.
>
> Iam positng via google groups using chrome, thats all i know.

It is becoming quite clear that some change has happened recently to
Google Groups that makes posts coming from there rather more obnoxious
than before. And there doesn't seem to be much its users can do except
use something else.

Using Google Groups for posting to Usenet has been a bad idea for a long
time, but now it just seems to be a sure recipe for annoying the rest of
us. Again, not something you have much control over, except to stop
using Google Groups.

-- 
 \  “Actually I made up the term “object-oriented”, and I can tell |
  `\you I did not have C++ in mind.” —Alan Kay, creator of |
_o__)Smalltalk, at OOPSLA 1997 |
Ben Finney
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Re: datetime issue

[Roy Smith]

In article <4f9d9a0b-539a-4b6a-af3e-b02d1f400...@googlegroups.com>,
 Íéêüëáïò Êïýñáò  wrote:


> Iam sorry i didnt do that on purpose and i dont know how this is done.
> 
> Iam positng via google groups using chrome, thats all i know.
> 
> Whats a mailing list?

Is it September already?
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Re: datetime issue

[Günther Dietrich]

In article ,
 Νικόλαος Κούρας  wrote:

[...]

>also it would be nice if datetime.datetime.now(GMT+2) can be used.

In , one of 
the first answers to your question you were pointed to pytz. This module 
does exactly what you ask for:

>>> import datetime
>>> import pytz
>>> greek_date = datetime.datetime.now(pytz.timezone('Europe/Athens'))
>>> greek_date
>>> print(greek_date)

If you do a help(pytz), obviously after having imported pytz, you will 
get some information about the module. At the end of this help, there 
are some attributes listed. One of them is all_timezones. Guess what it 
contains?



Best regards,

Günther




PS: I didn't know pytz yet. But it took me just five minutes of reading 
the datetime documentation and trying pytz.timezone(), to get a working 
example.
So I don't understand, why you didn't follow the proposal of trying 
pytz, but claimed, it wouldn't work.
Can you explain, why ist doesn't work for you rsp. what is the error 
when it doesn't work?
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Re: datetime issue

[Chris Angelico]

On Sun, Sep 16, 2012 at 11:22 PM, Roy Smith  wrote:
> In article <4f9d9a0b-539a-4b6a-af3e-b02d1f400...@googlegroups.com>,
>  Νικόλαος Κούρας  wrote:
>> Iam sorry i didnt do that on purpose and i dont know how this is done.
>>
>> Iam positng via google groups using chrome, thats all i know.
>>
>> Whats a mailing list?
>
> Is it September already?

Yes, it is; what does that mean in response to this question? Is there
something about September that causes the question, or is it a once
per month[1] question?

ChrisA
[1] http://tvtropes.org/pmwiki/pmwiki.php/Main/OncePerEpisode
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Re: datetime issue

[Chris Angelico]

On Mon, Sep 17, 2012 at 12:06 AM, Roy Smith  wrote:
> In article ,
>  Chris Angelico  wrote:
>
>> > Is it September already?
>>
>> Yes, it is; what does that mean in response to this question? Is there
>> something about September that causes the question, or is it a once
>> per month[1] question?
>
> http://en.wikipedia.org/wiki/Eternal_September

Ohh, yes. I do remember reading about that. Yes, it is definitely September.

Back in 1993, I wasn't yet started on networking. My dad ran things,
because I was only nine years old, and he definitely (and quite
rightly) didn't let me onto the internet. So I'm a tad young to know
about these things beyond what I've read in the history books...

ChrisA
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Re: newbie question : gedit as an ide

[Chris Angelico]

On Sun, Sep 16, 2012 at 9:52 PM, Mayuresh Kathe  wrote:
> new to the group, a quick hello to all.  :-)
> does anyone use gedit as an 'ide' for python development?
> if yes, may i know the caveats against using 'idle', 'bpython', etc?
>
> thank you.

I never really liked gedit; when I first switched my primary
development platform to Linux (from working on OS/2 and Windows), it
was an Ubuntu, and I felt that gedit was less than satisfactory. The
second GUI editor I tried was SciTE, which IMHO is distinctly
superior. Mainly, though, I don't use any sort of IDE per se; the only
"IDE-like" feature in my setup is SciTE's F7 key binding to run
'make', and then a properly-configured makefile in every directory
that I work in. Between that and a terminal window for git commands,
there's not really much more to look for in a development environment.

ChrisA
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Re: newbie question : gedit as an ide

[Devin Jeanpierre]

On Sun, Sep 16, 2012 at 7:52 AM, Mayuresh Kathe  wrote:
> new to the group, a quick hello to all.  :-)
> does anyone use gedit as an 'ide' for python development?
> if yes, may i know the caveats against using 'idle', 'bpython', etc?

bpython isn't an IDE, it's a good interactive interpreter.

As for gedit as an editor... it's actually really bad, but fixable if
you install plugins. e.g., it doesn't have builtin support for case
sensitive / regexp search and so on, but these can be added so that
gedit becomes tolerable. In fact, one of gedit's main advantages over
many of its similar competitors (in particular I'm thinking of Kate)
is that the plugin support is very strong, so if it doesn't do what
you want, you can make it do what you want anyway.

So, install / enable plugins. Lots of them. Or use an editor designed
for programmers first, such as Kate or vim or emacs.

-- Devin
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Re: Moving folders with content

[Nobody]

On Sun, 16 Sep 2012 12:40:18 +0200, Hans Mulder wrote:

> But you should get into the habit of using shell=False whenever
> possible, because it is much easier to get it right.

More accurately, you should get into the habit of passing a list as the
first argument, rather than a string.

On Unix-like systems (including Mac OS X), this effectively requires
shell=False. Passing a list with shell=True has behaviour which is
well-defined, but rarely useful (the first element of the list will be
executed as a shell command, the remaining elements will be available via
the shell variables $1, $2, etc within that command).

On Windows, the list is converted to a command string using the same
quoting rules regardless of the value of the shell= parameter. The
difference is that shell=False requires the "executable" to actually be a
binary executable, while shell=True allows it to be some other type of
file (e.g. a batch file, Python script, etc).

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newbie question About O'Reilly "Python for Unix and Linux System Administration" ftp Mirror question

[moonhkt]

Hi All


O'Reilly Book ISBN 978-986-6840-36-4.

python --version
Python 2.6.2 on AIX 5.3

Using this python to get files in ftp server.

I got below error. What is the error meaning and how to fix ?

ftp_mirror.py
Traceback (most recent call last):
  File "/xx../shell/ftpmirror.py", line 80, in 
f = FTPSync(options.host, options.username, options.password,
options.remote_dir, options.local_dir, opti
ons.delete)
  File "xx../shell/ftpmirror.py", line 17, in __init__
self.conn.cwd(ftp_base_dir)
  File "/opt/freeware/lib/python2.6/ftplib.py", line 536, in cwd
cmd = 'CWD ' + dirname
TypeError: cannot concatenate 'str' and 'NoneType' objects

Source :

#!/usr/bin/env python

import ftplib
import os

class FTPSync(object):
def __init__(self, host, username, password, ftp_base_dir,
local_base_dir, delete=False):
self.host = host
self.username = username
self.password = password
self.ftp_base_dir = ftp_base_dir
self.local_base_dir = local_base_dir
self.delete = delete

self.conn = ftplib.FTP(host, username, password)
self.conn.cwd(ftp_base_dir)
try:
os.makedirs(local_base_dir)
except OSError:
pass
os.chdir(local_base_dir)
def get_dirs_files(self):
dir_res = []
self.conn.dir('.', dir_res.append)
files = [f.split(None, 8)[-1] for f in dir_res if
f.startswith('-')]
dirs = [f.split(None, 8)[-1] for f in dir_res if
f.startswith('d')]
return (files, dirs)
def walk(self, next_dir):
print "Walking to", next_dir
self.conn.cwd(next_dir)
try:
os.mkdir(next_dir)
except OSError:
pass
os.chdir(next_dir)

ftp_curr_dir = self.conn.pwd()
local_curr_dir = os.getcwd()

files, dirs = self.get_dirs_files()
print "FILES:", files
print "DIRS:", dirs
for f in files:
print next_dir, ':', f
outf = open(f, 'wb')
try:
self.conn.retrbinary('RETR %s' % f, outf.write)
finally:
outf.close()
if self.delete:
print "Deleting", f
self.conn.delete(f)
for d in dirs:
os.chdir(local_curr_dir)
self.conn.cwd(ftp_curr_dir)
self.walk(d)

def run(self):
self.walk('.')


if __name__ == '__main__':
from optparse import OptionParser
parser = OptionParser()
parser.add_option("-o", "--host", dest="host",
 action='store', help="FTP host")
parser.add_option("-u", "--username", dest="username",
 action='store', help="FTP username")
parser.add_option("-p", "--password", dest="password",
 action='store', help="FTP password")
parser.add_option("-r", "--remote_dir", dest="remote_dir",
 action='store', help="FTP remote starting directory")
parser.add_option("-l", "--local_dir", dest="local_dir",
 action='store', help="Local starting directory")
parser.add_option("-d", "--delete", dest="delete", default=False,
 action='store_true', help="use regex parser")

(options, args) = parser.parse_args()
f = FTPSync(options.host, options.username, options.password,
options.remote_dir, options.local_dir, options.delete)
f.run()

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Re: datetime issue

[MRAB]

On 2012-09-16 09:25, Νικόλαος Κούρας wrote:
[snip]


date = ( datetime.datetime.now() + datetime.timedelta(hours=8) ).strftime( 
'%y-%m-%d %H:%M:%S')

but iam giving +8 hours which is the time difference between texas, us where 
the server sits and Greece's time.

cant we somehow tell it to use GMT+2 ?

also it would be nice if datetime.datetime.now(GMT+2) can be used.


In programming, you need attention to details.

My reply didn't use datetime.datetime.now(), it used 
datetime.datetime.utcnow().


datetime.datetime.now() gives the local time (local to the system on 
which it is running).


datetime.datetime.utcnow() gives the UTC (GMT) time, which is the same 
everywhere.


The line should be this:

date = (datetime.datetime.utcnow() + datetime.timedelta(hours=8) 
).strftime('%Y-%m-%d %H:%M:%S')


I've also used '%Y' instead of '%y' because I prefer 4 digits for the year.

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Re: newbie question About O'Reilly "Python for Unix and Linux System Administration" ftp Mirror question

[Joel Goldstick]

On Sun, Sep 16, 2012 at 11:09 AM, moonhkt  wrote:
> Hi All
>
>
> O'Reilly Book ISBN 978-986-6840-36-4.
>
> python --version
> Python 2.6.2 on AIX 5.3
>
> Using this python to get files in ftp server.
>
> I got below error. What is the error meaning and how to fix ?
>
> ftp_mirror.py
> Traceback (most recent call last):
>   File "/xx../shell/ftpmirror.py", line 80, in 
> f = FTPSync(options.host, options.username, options.password,
> options.remote_dir, options.local_dir, opti
> ons.delete)
>   File "xx../shell/ftpmirror.py", line 17, in __init__
> self.conn.cwd(ftp_base_dir)
>   File "/opt/freeware/lib/python2.6/ftplib.py", line 536, in cwd
> cmd = 'CWD ' + dirname
> TypeError: cannot concatenate 'str' and 'NoneType' objects
>
> Source :
>
> #!/usr/bin/env python
>
> import ftplib
> import os
>
> class FTPSync(object):
> def __init__(self, host, username, password, ftp_base_dir,
> local_base_dir, delete=False):
> self.host = host
> self.username = username
> self.password = password
> self.ftp_base_dir = ftp_base_dir
> self.local_base_dir = local_base_dir
> self.delete = delete
>
> self.conn = ftplib.FTP(host, username, password)
> self.conn.cwd(ftp_base_dir)
> try:
> os.makedirs(local_base_dir)
> except OSError:
> pass
> os.chdir(local_base_dir)
> def get_dirs_files(self):
> dir_res = []
> self.conn.dir('.', dir_res.append)
> files = [f.split(None, 8)[-1] for f in dir_res if
> f.startswith('-')]
> dirs = [f.split(None, 8)[-1] for f in dir_res if
> f.startswith('d')]
> return (files, dirs)
> def walk(self, next_dir):
> print "Walking to", next_dir
> self.conn.cwd(next_dir)
> try:
> os.mkdir(next_dir)
> except OSError:
> pass
> os.chdir(next_dir)
>
> ftp_curr_dir = self.conn.pwd()
> local_curr_dir = os.getcwd()
>
> files, dirs = self.get_dirs_files()
> print "FILES:", files
> print "DIRS:", dirs
> for f in files:
> print next_dir, ':', f
> outf = open(f, 'wb')
> try:
> self.conn.retrbinary('RETR %s' % f, outf.write)
> finally:
> outf.close()
> if self.delete:
> print "Deleting", f
> self.conn.delete(f)
> for d in dirs:
> os.chdir(local_curr_dir)
> self.conn.cwd(ftp_curr_dir)
> self.walk(d)
>
> def run(self):
> self.walk('.')
>
>
> if __name__ == '__main__':
> from optparse import OptionParser
> parser = OptionParser()
> parser.add_option("-o", "--host", dest="host",
>  action='store', help="FTP host")
> parser.add_option("-u", "--username", dest="username",
>  action='store', help="FTP username")
> parser.add_option("-p", "--password", dest="password",
>  action='store', help="FTP password")
> parser.add_option("-r", "--remote_dir", dest="remote_dir",
>  action='store', help="FTP remote starting directory")
> parser.add_option("-l", "--local_dir", dest="local_dir",
>  action='store', help="Local starting directory")
> parser.add_option("-d", "--delete", dest="delete", default=False,
>  action='store_true', help="use regex parser")
>
> (options, args) = parser.parse_args()
comment the next line , then print the parameters and see what they
are.  That should get you started.
> #f = FTPSync(options.host, options.username, options.password,
> #options.remote_dir, options.local_dir, options.delete)
  f = print(options.host, options.username, options.password,
  options.remote_dir, options.local_dir, options.delete)


> f.run()
>
> --
> http://mail.python.org/mailman/listinfo/python-list



-- 
Joel Goldstick
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Re: datetime issue

[pandora . koura]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 6:30:15 μ.μ. UTC+3, ο χρήστης MRAB έγραψε:
> On 2012-09-16 09:25, Νικόλαος Κούρας wrote:
> 
> [snip]
> 
> >
> 
> > date = ( datetime.datetime.now() + datetime.timedelta(hours=8) ).strftime( 
> > '%y-%m-%d %H:%M:%S')
> 
> >
> 
> > but iam giving +8 hours which is the time difference between texas, us 
> > where the server sits and Greece's time.
> 
> >
> 
> > cant we somehow tell it to use GMT+2 ?
> 
> >
> 
> > also it would be nice if datetime.datetime.now(GMT+2) can be used.
> 
> >
> 
> In programming, you need attention to details.
> 
> 
> 
> My reply didn't use datetime.datetime.now(), it used 
> 
> datetime.datetime.utcnow().
> 
> 
> 
> datetime.datetime.now() gives the local time (local to the system on 
> 
> which it is running).
> 
> 
> 
> datetime.datetime.utcnow() gives the UTC (GMT) time, which is the same 
> 
> everywhere.
> 
> 
> 
> The line should be this:
> 
> 
> 
> date = (datetime.datetime.utcnow() + datetime.timedelta(hours=8) 
> 
> ).strftime('%Y-%m-%d %H:%M:%S')
> 
> 
> 
> I've also used '%Y' instead of '%y' because I prefer 4 digits for the year.

Cant it be written more easily as:
 date = (datetime.datetime.utcnow(+2)

i know this is not thhe correct syntax but it just needs a way to add GMT+2 
hours since utc=gmt
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Re: newbie question About O'Reilly "Python for Unix and Linux System Administration" ftp Mirror question

[Chris Angelico]

On Mon, Sep 17, 2012 at 1:09 AM, moonhkt  wrote:
> Hi All
>
> O'Reilly Book ISBN 978-986-6840-36-4.
>
> python --version
> Python 2.6.2 on AIX 5.3

Hi! Thanks for this, good information to open with.

> Using this python to get files in ftp server.
>
> I got below error. What is the error meaning and how to fix ?
>
> ftp_mirror.py
> Traceback (most recent call last):
>   File "/xx../shell/ftpmirror.py", line 80, in 
> f = FTPSync(options.host, options.username, options.password,
> options.remote_dir, options.local_dir, opti
> ons.delete)
>   File "xx../shell/ftpmirror.py", line 17, in __init__
> self.conn.cwd(ftp_base_dir)
>   File "/opt/freeware/lib/python2.6/ftplib.py", line 536, in cwd
> cmd = 'CWD ' + dirname
> TypeError: cannot concatenate 'str' and 'NoneType' objects

NoneType is the type of the singleton object None. Why are you getting
None where you ought to be providing a directory name? Heavily trimmed
code follows:

> def __init__(self, host, username, password, ftp_base_dir,
> local_base_dir, delete=False):
> self.conn.cwd(ftp_base_dir)
> parser.add_option("-r", "--remote_dir", dest="remote_dir",
>  action='store', help="FTP remote starting directory")
> f = FTPSync(options.host, options.username, options.password,
> options.remote_dir, options.local_dir, options.delete)

If you don't pass -r/--remote_dir to your script, then (presumably - I
haven't actually used optparse so this is glarked from context)
options.remote_dir is being set to, or left at, None. A quick look at
the docs suggests that one solution is to add a default value to the
options:

http://docs.python.org/library/optparse.html#default-values

Alternatively, treat the options as mandatory, and provide them on the
command line.

Side point: When you go to the docs page there, you may notice that
optparse is deprecated in favour of argparse. May as well continue the
tutorial with what they recommend, but it's probably worth having a
look at argparse eventually.

Hope that helps!

Chris Angelico
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Re: datetime issue

[pandora . koura]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 4:23:02 μ.μ. UTC+3, ο χρήστης Günther Dietrich 
έγραψε:
> In article ,
> 
>  Νικόλαος Κούρας  wrote:
> 
> 
> 
> [...]
> 
> 
> 
> >also it would be nice if datetime.datetime.now(GMT+2) can be used.
> 
> 
> 
> In , one of 
> 
> the first answers to your question you were pointed to pytz. This module 
> 
> does exactly what you ask for:
> 
> 
> 
> >>> import datetime
> 
> >>> import pytz
> 
> >>> greek_date = datetime.datetime.now(pytz.timezone('Europe/Athens'))
> 
> >>> greek_date
> 
> >>> print(greek_date)
> 
> 
> 
> If you do a help(pytz), obviously after having imported pytz, you will 
> 
> get some information about the module. At the end of this help, there 
> 
> are some attributes listed. One of them is all_timezones. Guess what it 
> 
> contains?
> 
> 
> 
> 
> 
> 
> 
> Best regards,
> 
> 
> 
> Günther
> 
> 
> 
> 
> 
> 
> 
> 
> 
> PS: I didn't know pytz yet. But it took me just five minutes of reading 
> 
> the datetime documentation and trying pytz.timezone(), to get a working 
> 
> example.
> 
> So I don't understand, why you didn't follow the proposal of trying 
> 
> pytz, but claimed, it wouldn't work.
> 
> Can you explain, why ist doesn't work for you rsp. what is the error 
> 
> when it doesn't work?

import pytz fails in my webhost unfortunately :(
This module is not supported by hostgator.
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[pandora . koura]

Τη Κυριακή, 16 Σεπτεμβρίου 2012 4:18:50 μ.μ. UTC+3, ο χρήστης Ben Finney έγραψε:
> Νικόλαος Κούρας  writes:
> 
> 
> 
> > Iam sorry i didnt do that on purpose and i dont know how this is done.
> 
> >
> 
> > Iam positng via google groups using chrome, thats all i know.
> 
> 


> 
> It is becoming quite clear that some change has happened recently to
> 
> Google Groups that makes posts coming from there rather more obnoxious
> 
> than before. And there doesn't seem to be much its users can do except
> 
> use something else.
> 
> 
> 
> Using Google Groups for posting to Usenet has been a bad idea for a long
> 
> time, but now it just seems to be a sure recipe for annoying the rest of
> 
> us. Again, not something you have much control over, except to stop
> 
> using Google Groups.
> 
> 
> 
> -- 
> 
>  \  “Actually I made up the term “object-oriented”, and I can tell |
> 
>   `\you I did not have C++ in mind.” —Alan Kay, creator of |
> 
> _o__)Smalltalk, at OOPSLA 1997 |
> 
> Ben Finney


If i ditch google groups what application can i use in Windows 8 to post to 
this newsgroup and what newsserver too?
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[pandora . koura]

Whaen i tried to post just now by hitting sumbit, google groups told me that 
the following addresssed has benn found in this thread! i guess is used them 
all to notify everything!

cdf072b2-7359-4417-b1e4-d984e4317...@googlegroups.com
mailman.774.1347735926.27098.python-l...@python.org
nikos.gr...@gmail.com
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Re: datetime issue

[Chris Angelico]

On Mon, Sep 17, 2012 at 1:40 AM,   wrote:
> Cant it be written more easily as:
>  date = (datetime.datetime.utcnow(+2)
>
> i know this is not thhe correct syntax but it just needs a way to add GMT+2 
> hours since utc=gmt

I've dithered about whether to open this can of worms or let sleeping
dogs lie, and I finally decided to make some metaphor potpourri.

Simple UTC offsets are not the same thing as local time. There are a
variety of other considerations, but the main one is Daylight Robbery
Time, where every government wants to put its own stamp on things by
fiddling with the DST rules a bit. Most places will move their clocks
an hour forward for summer and then back for winter. But!

* Some places are sensible and don't have DST at all (eg
Australia/Queensland, America/Arizona)
* Northern hemisphere summer corresponds to southern hemisphere
winter, and vice versa
* Everyone has a different way of defining the boundaries of summer and winter
* And just to confuse us all, Irish Standard Time is used in summer,
and they *subtract* an hour for winter time!

The only way to handle timezones correctly and keep yourself even
marginally sane is to hand the job on to somebody else. I dodged the
whole issue by letting our Postgres database handle everything for us
(date/time formats, timezones, the lot), and having our internal
systems all just work in UTC. You'll likely find it easiest to do the
same thing with a Python library.

Just don't try to pretend to yourself that Greece uses GMT+2, because
it's not that simple. For one thing, it's currently summer there...

ChrisA
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[Chris Angelico]

On Mon, Sep 17, 2012 at 1:44 AM,   wrote:
> Whaen i tried to post just now by hitting sumbit, google groups told me that 
> the following addresssed has benn found in this thread! i guess is used them 
> all to notify everything!
>
> cdf072b2-7359-4417-b1e4-d984e4317...@googlegroups.com
> mailman.774.1347735926.27098.python-l...@python.org
> nikos.gr...@gmail.com

Ah. Did you then send to all three? Just a wild guess, but I'm
thinking that might be the cause of post duplication...

ChrisA
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[pandora . koura]

> 
> > http://mail.python.org/mailman/listinfo/python-list
> 
> 
> 
> email client to python-list@python.org
> 

wait a minute! i must use my ISP's news server and then post o comp.lang.python 
no?

What is python-list@python.org how can i post there?
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[Joel Goldstick]

On Sun, Sep 16, 2012 at 11:41 AM,   wrote:
> Τη Κυριακή, 16 Σεπτεμβρίου 2012 4:18:50 μ.μ. UTC+3, ο χρήστης Ben Finney 
> έγραψε:
>> Νικόλαος Κούρας  writes:
>>
>>
>>
>> > Iam sorry i didnt do that on purpose and i dont know how this is done.
>>
>> >
>>
>> > Iam positng via google groups using chrome, thats all i know.
>>
>>
>
>
>>
>> It is becoming quite clear that some change has happened recently to
>>
>> Google Groups that makes posts coming from there rather more obnoxious
>>
>> than before. And there doesn't seem to be much its users can do except
>>
>> use something else.
>>
>>
>>
>> Using Google Groups for posting to Usenet has been a bad idea for a long
>>
>> time, but now it just seems to be a sure recipe for annoying the rest of
>>
>> us. Again, not something you have much control over, except to stop
>>
>> using Google Groups.
>>
>>
>>
>> --
>>
>>  \  “Actually I made up the term “object-oriented”, and I can tell |
>>
>>   `\you I did not have C++ in mind.” —Alan Kay, creator of |
>>
>> _o__)Smalltalk, at OOPSLA 1997 |
>>
>> Ben Finney
>
>
> If i ditch google groups what application can i use in Windows 8 to post to 
> this newsgroup and what newsserver too?
> --
> http://mail.python.org/mailman/listinfo/python-list

email client to python-list@python.org



-- 
Joel Goldstick
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Obnoxious postings from Google Groups (was: datetime issue)

[pandora . koura]

> 
> Ah. Did you then send to all three? Just a wild guess, but I'm
> 
> thinking that might be the cause of post duplication...
> 
> 
> 
> ChrisA

I had no choise, it doesnt let me pick one, it just notifies me that it will 
posted to these 3.
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Re: Python presentations

[Alexander Blinne]

On 14.09.2012 14:19, Chris Angelico wrote:
> Err, yes, I did mean ** there. The extra multiplications may be
> slower, but which is worse? Lots of list additions, or lots of integer
> powers? In the absence of clear and compelling evidence, I'd be
> inclined to go with the list comp - and what's more, to skip this
> function altogether and use the list comp directly where it's needed.

I did some timing with the following versions of the function:

def powerlist1(x, n):
result=[1]
for i in xrange(n-1):
result.append(result[-1]*x)
return result

def powerlist2(x,n):
if n==1:
return [1]
p = powerlist3(x,n-1)
p.append(p[-1]*x)
return p

def powerlist3(x,n):
  return [x**i for i in xrange(n)]

with Python 2.7 you are quite right, i used x=4. Below n=26 powerlist3
is the fastest version, for n>26 powerlist1 is faster, powerlist2 is
always slower than both.

With Pypy there is a completely different picture, with n<30 powerlist2
is way faster then the other two, but then powerlist1 is again faster
for greater n, somehow because now C long int cannot be used any longer.

for really big n powerlist3 always takes very much time :)

Alex
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Re: Python presentations

[Chris Angelico]

On Mon, Sep 17, 2012 at 2:13 AM, Alexander Blinne  wrote:
> def powerlist3(x,n):
>   return [x**i for i in xrange(n)]
>
> for really big n powerlist3 always takes very much time :)

I would reiterate that a really big n is a really unusual use case for
a function like this, except that... I frankly can't think of *any*
use case for it!! But for many many applications, the simplicity and
readability of a list comp instead of a function is usually going to
outweigh the performance differences.

However, it doesn't surprise me that individually raising a number to
successive powers is slower than iterative multiplication, assuming
you can't massively optimize eg with powers of 2 and bit shifts.

ChrisA
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[Joel Goldstick]

On Sun, Sep 16, 2012 at 12:06 PM,   wrote:
>
>>
>> > http://mail.python.org/mailman/listinfo/python-list
>>
>>
>>
>> email client to python-list@python.org
>>
>
> wait a minute! i must use my ISP's news server and then post o 
> comp.lang.python no?
>
> What is python-list@python.org how can i post there?
> --
> http://mail.python.org/mailman/listinfo/python-list

go to the url http://mail.python.org/mailman/listinfo/python-list

sign up and use your email client instead.

-- 
Joel Goldstick
-- 
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testing....

[Nick the Gr33k]

Test to see if it works.
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Re: Obnoxious postings from Google Groups

[Terry Reedy]

On 9/16/2012 11:41 AM, pandora.ko...@gmail.com wrote:


If i ditch google groups


PLEASE DO

> what application can i use in Windows 8 to post to this newsgroup
> and what newsserver too?

news.gmane.org is a free newsserver that mirrors 1000s of technical 
email lists. python-list is gmane.comp.python.general. There are 100s of 
other gmane.comp.python.* groups.


I use Thunderbird on Win7 because it does both mail and news. I 
previously used Outlook Express for same. There are others.


--
Terry Jan Reedy

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Re: Obnoxious postings from Google Groups (was: datetime issue)

[Gene Heskett]

On Sunday 16 September 2012 12:08:47 pandora.ko...@gmail.com did opine:

> Whaen i tried to post just now by hitting sumbit, google groups told me
> that the following addresssed has benn found in this thread! i guess is
> used them all to notify everything!
> 
> cdf072b2-7359-4417-b1e4-d984e4317...@googlegroups.com
> mailman.774.1347735926.27098.python-l...@python.org
> nikos.gr...@gmail.com

Look, this googlegroups thing acting as a spam gateway has long since 
gotten old.  Whatever agent/program you are using must be a busted windows 
application because it is not showing you the last line of every post that 
comes through the list server which is:



There is, immediately above that line a '-- ' (note the space after, and 
its always after a linefeed or carriage return so its the first character 
of a line, and its code to all sane email agents that anything below it is 
a signature and not to be copied into a reply.  Windows email tends to clip 
it off and a windows user will never see it!  So that is why many of us 
lament, in long strings of expletives, the brokenness of windows email 
agents.

Subscribing to the mailing list is a 2 step process.  First you click on 
the above link and fill out the form and "submit" it.

That will, in a minute or so, cause an email to be sent to the address you 
used in the form.  You MUST reply to that message to confirm the 
subscription.  Whatever email agent you use from there is up to you, but 
I'd suggest Thunderbird.  I personally am partial to kmail, but then I'm 
running linux on everything here, no M$ stuff allowed on the premises.  Its 
not open for discussion and has not been in 28 years since I discovered the 
trs-80 color computer and an operating system for it called OS9.

Sorry folks, my rant for the day because of that gateway.

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page:  is up!
Succumb to natural tendencies.  Be hateful and boring.
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[Steven D'Aprano]

On Sun, 16 Sep 2012 08:41:44 -0700, pandora.koura wrote:

> If i ditch google groups what application can i use in Windows 8 to post
> to this newsgroup and what newsserver too?

Google is your friend. Do try to find the answer to your questions before 
asking here.

Search for "usenet news reader application". Or use Thunderbird.

For the news server, you use your ISP's newserver, if they offer one, or 
Gmane, or any of dozens of commercial news providers who will give you 
access to one for a small fee.


-- 
Steven
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[Steven D'Aprano]

On Sun, 16 Sep 2012 09:06:30 -0700, pandora.koura wrote:


>> > http://mail.python.org/mailman/listinfo/python-list


> What is python-list@python.org how can i post there?

It's the same thing it was when I posted the above URL a few hours ago.

Didn't you follow the link before? It has instructions there.



-- 
Steven
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Using Py_AddPendingCall

[css322]

I have an embedded Python program which runs in a thread in C.

When the Python interpreter switches thread context (yielding control to 
another thread), I'd like to be notified so I can perform certain necessary 
operations.

It seems that Py_AddPendingCall is exactly what I'm looking for. However, the 
API docs are pretty brief on this function, and I'm confused as to how 
Py_AddPendingCall is supposed to be used. From reading the docs, my 
understanding is that:

(1) A worker thread calls Py_AddPendingCall and assigns a handler function.
(2) When the Python interpreter runs, it calls the handler function whenever it 
yields control to another thread
(3) The handler itself is executed in the main interpreter thread, with the GIL 
acquired

I've googled around for example code showing how to use Py_AddPendingCall, but 
I can't find anything. My own attempt to use it simply doesn't work. The 
handler is just never called.

My worker thread code:

const char* PYTHON_CODE = 
"while True:\n"
"   for i in range(0,10): print(i)\n"
"\n";

int handler(void* arg)
{
printf("Pending Call invoked!\n");
abort();
}

void worker_thread()
{
PyGILState_STATE state = PyGILState_Ensure();
Py_AddPendingCall(&handler, NULL);
PyRun_SimpleString(PYTHON_CODE);
PyGILState_Release(state);
}

In this example, worker_thread is invoked in C as a pthread worker thread. This 
loops infinitely, but the pending call handler is never invoked.

So,obviously I'm not understanding the docs correctly.  How is 
Py_AddPendingCall is supposed to be used?
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Re: Python presentations

[Steven D'Aprano]

On Sun, 16 Sep 2012 18:13:36 +0200, Alexander Blinne wrote:

> I did some timing with the following versions of the function:
> 
> def powerlist1(x, n):
> result=[1]
> for i in xrange(n-1):
> result.append(result[-1]*x)
> return result
> 
> def powerlist2(x,n):
> if n==1:
> return [1]
> p = powerlist3(x,n-1)
> p.append(p[-1]*x)
> return p

Is that a typo? I think you mean to make a recursive call to powerlist2, 
not a non-recursive call to powerlist3.


> def powerlist3(x,n):
>   return [x**i for i in xrange(n)]
> 
> with Python 2.7 you are quite right, i used x=4. Below n=26 powerlist3
> is the fastest version, for n>26 powerlist1 is faster, powerlist2 is
> always slower than both.

Making powerlist2 recursive, the results I get with Python 2.7 are:


py> from timeit import Timer as T
py> x = 2.357
py> n = 8
py> t1 = T('powerlist1(x, n)', 
...  setup='from __main__ import powerlist1, x, n')
py> t2 = T('powerlist2(x, n)', 
...  setup='from __main__ import powerlist2, x, n')
py> t3 = T('powerlist3(x, n)', 
...  setup='from __main__ import powerlist3, x, n')
py> min(t1.repeat(number=10, repeat=5))
0.38042593002319336
py> min(t2.repeat(number=10, repeat=5))
0.5992050170898438
py> min(t3.repeat(number=10, repeat=5))
0.334306001663208

So powerlist2 is half as fast as the other two, which are very close.

For large n, #1 and #3 are still neck-and-neck:

py> n = 100
py> min(t1.repeat(number=10, repeat=5))
3.6276791095733643
py> min(t3.repeat(number=10, repeat=5))
3.58870792388916

which is what I would expect: the overhead of calling Python code will be 
greater than the speed up from avoiding float multiplications. But long 
integer unlimited-precision multiplications are slow. To really see the 
advantage of avoiding multiplications using Horner's Method (powerlist1), 
we need to use large integers and not floats.

py> x = 12345678*1
py> n = 3
py> min(t1.repeat(number=10, repeat=5))
0.2199108600616455
py> min(t3.repeat(number=10, repeat=5))
0.551645040512085

As n becomes bigger, the advantage also increases:

py> n = 10
py> min(t1.repeat(number=10, repeat=5))
0.736515998840332
py> min(t3.repeat(number=10, repeat=5))
2.4837491512298584

In this case with n = 10, powerlist1 does 9 multiplications. But 
powerlist3 makes ten calls to the ** operator. The number of 
multiplications will depend on how cleverly exponentiation is 
implemented: at worst, using a naive algorithm, there will be 36 
multiplications. If the algorithm is a bit smarter, there will be 19 
multiplications.

Either way, when the calculation is dominated by the cost of 
multiplication, powerlist3 is between two and four times as expensive as 
powerlist1.


-- 
Steven
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RE: Moving folders with content

[jyoung79]

Hi "Nobody" and Hans,

I really appreciate you all sharing this insight with me.

> You might think that os.path.expanduser
> would never expand '~' to something containing a double quote,
> but you'd be wrong:

> >>> import os
> >>> os.environ['HOME'] = 'gotcha!"; rm -rf '
> >>> print(os.path.expanduser('~/Desktop/IN/Test/'))
> gotcha!"; rm -rf /Desktop/IN/Test/
> 
> It's easy and safer to avoid using 'shell=True' option:
> 
> cmd = ['ditto', '-vV', p1, p2]
> v = subprocess.check_output(cmd, shell=False)

I would have never thought about this, and this could definitely 
give me problems.  Thank you for this advice!

Again, thank you both for the examples and deeper understanding 
of how subprocess works.  I will definitely start passing a list 
as the first argument as well as updating my older code to do 
the same.

Jay
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Re: unit test strategy

[Aaron Brady]

On Sunday, September 16, 2012 2:42:09 AM UTC-5, Steven D'Aprano wrote:
> On Fri, 14 Sep 2012 19:59:29 -0700, Aaron Brady wrote:
> 
> 
> 
> > Hello,
> 
> > 
> 
> > I've developing a test script.  There's a lot of repetition.  I want to
> 
> > introduce a strategy for approaching it, but I don't want the program to
> 
> > be discredited because of the test script.
> 
> 
> 
> Test scripts should be simple enough that they don't require test scripts 
> 
> of their own. Or at least, not too many "test-the-test" tests. It is 
> 
> possible to avoid repetition without making convoluted, hard to 
> 
> understand code. Based on the tiny code fragments you give below, I 
> 
> suspect that your test script will need more testing than the code it 
> 
> tests!
> 
> 
> 
> 
> 
> > Therefore, I'd like to know
> 
> > what people's reactions to and thoughts about it are.
> 
> 
> 
> I'd love to make some suggestions, but I have *no idea* what you are 
> 
> talking about. See further comments below:
> 
> 
> 
> 
> 
> > The first strategy I used created an iterator and advanced it between
> 
> > each step:
> 
> 
> 
> What are you using an iterator for? What does this have to do with unit 
> 
> testing?
> 
> 
> 
> So far, your explanation is rather lacking. It's a bit like:
> 
> 
> 
> "I want to create an alarm system for my home, so I put in a screw and 
> 
> tightened it after each step."
> 
> 
> 
> Doesn't really help us understand what you are doing.
> 
> 
> 
> 
> 
> > self.op_chain(range(5), ('add', 5))
> 
> > self.op_chain(range(5), ('add', -2), ('add', -1))
> 
> > self.op_chain(range(5), ('discard', -1), ('add', 5))
> 
> > self.op_chain_ok(range(5), ('update', [0, 1]))
> 
> > Etc.
> 
> 
> 
> Where is the iterator you created? Where are you advancing it? What's 
> 
> op_chain do?
> 
> 
> 
> 
> 
> > I'm considering something more complicated.  'iN' creates iterator N,
> 
> > 'nN' advances iterator N, an exception calls 'assertRaises', and the
> 
> > rest are function calls.
> 
> [...]
> 
> 
> 
> You've proven that even in Python people can write obfuscated code.
> 
> 
> 
> 
> 
> > Do you think the 2nd version is legible?
> 
> 
> 
> Neither version is even close to legible.
> 
> 
> 
> 
> 
> > Could it interfere with the accuracy of the test?
> 
> 
> 
> Who knows? I have no clue what your code is doing, it could be doing 
> 
> *anything*.
> 
> 
> 
> 
> 
> 
> 
> -- 
> 
> Steven

You are forcing me to explain my test code.

Here is an example of some repetitive code.

for view_meth in [ dict.items, dict.keys, dict.values ]:
dict0= dict( ( k, None ) for k in range( 10 ) )
iter0= iter( view_meth( dict0 ) )
dict.__setitem__( dict0, 0, 1 )
next( iter0 )
dict.__setitem__( dict0, 10, 1 )
self.assertRaises( IterationError, next, iter0 )

dict0= dict( ( k, None ) for k in range( 10 ) )
iter0= iter( view_meth( dict0 ) )
next( iter0 )
dict.__setitem__( dict0, 0, 1 )
next( iter0 )
dict.__setitem__( dict0, 10, 1 )
self.assertRaises( IterationError, next, iter0 )

dict0= dict( ( k, None ) for k in range( 10 ) )
iter0= iter( view_meth( dict0 ) )
self.assertRaises( KeyError, dict0.__delitem__, 10 )
next( iter0 )
dict.__delitem__( dict0, 9 )
self.assertRaises( IterationError, next, iter0 )

dict0= dict( ( k, None ) for k in range( 10 ) )
iter0= iter( view_meth( dict0 ) )
next( iter0 )
self.assertRaises( KeyError, dict0.__delitem__, 10 )
next( iter0 )
dict.__delitem__( dict0, 9 )
self.assertRaises( IterationError, next, iter0 )


It makes sense to condense it.  However, it can be condensed rather far, as 
follows:

dsi= dict.__setitem__
ddi= dict.__delitem__
KE= KeyError
IE= IterationError
chain(range(10), 'i0', (dsi, 0, 1), 'n0', (dsi, 10, 1), (IE, 'n0'))
chain(range(10), 'i0', 'n0', (dsi, 0, 1), 'n0', (dsi, 10, 1), (IE, 'n0'))
chain(range(10), 'i0', (KE, ddi, 10), 'n0', (ddi, 9), (IE, 'n0'))
chain(range(10), 'i0', 'n0', (KE, ddi, 10), 'n0', (ddi, 9), (IE, 'n0'))


The parameters to 'chain' correspond 1-to-1 with the statements earlier.  The 
view methods are looped over in the 'chain' method instead.  'op_chain' was an 
earlier version; some midway point in condensing the code could be preferable.

Specifically my questions are, is the code condensed beyond legibility?  Should 
'chain' execute the test directly, or act as a metaprogram and output the test 
code into a 2nd file, or both?  Should 'chain' create the iterators in a 
dictionary, or in the function local variables directly with 'exec'?
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Re: datetime issue

[Mark Lawrence]

On 16/09/2012 16:54, Chris Angelico wrote:

On Mon, Sep 17, 2012 at 1:40 AM,   wrote:

Cant it be written more easily as:
  date = (datetime.datetime.utcnow(+2)

i know this is not thhe correct syntax but it just needs a way to add GMT+2 
hours since utc=gmt


I've dithered about whether to open this can of worms or let sleeping
dogs lie, and I finally decided to make some metaphor potpourri.

Simple UTC offsets are not the same thing as local time. There are a
variety of other considerations, but the main one is Daylight Robbery
Time, where every government wants to put its own stamp on things by
fiddling with the DST rules a bit. Most places will move their clocks
an hour forward for summer and then back for winter. But!

* Some places are sensible and don't have DST at all (eg
Australia/Queensland, America/Arizona)
* Northern hemisphere summer corresponds to southern hemisphere
winter, and vice versa
* Everyone has a different way of defining the boundaries of summer and winter
* And just to confuse us all, Irish Standard Time is used in summer,
and they *subtract* an hour for winter time!

The only way to handle timezones correctly and keep yourself even
marginally sane is to hand the job on to somebody else. I dodged the
whole issue by letting our Postgres database handle everything for us
(date/time formats, timezones, the lot), and having our internal
systems all just work in UTC. You'll likely find it easiest to do the
same thing with a Python library.

Just don't try to pretend to yourself that Greece uses GMT+2, because
it's not that simple. For one thing, it's currently summer there...

ChrisA



I guess that Double British Summer Time made things twice as difficult?

--
Cheers.

Mark Lawrence.

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Re: Obnoxious postings from Google Groups

[Mark Lawrence]

On 16/09/2012 17:06, pandora.ko...@gmail.com wrote:





http://mail.python.org/mailman/listinfo/python-list




email client to python-list@python.org



wait a minute! i must use my ISP's news server and then post o comp.lang.python 
no?

What is python-list@python.org how can i post there?



I'm on Windows Vista and read many Python mailing lists with Thunderbird 
via gmane.


--
Cheers.

Mark Lawrence.

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Re: datetime issue

[Dave Angel]

On 09/16/2012 07:56 AM, Νικόλαος Κούρας wrote:
> Τη Κυριακή, 16 Σεπτεμβρίου 2012 2:34:34 μ.μ. UTC+3, ο χρήστης Steven D'Aprano 
> έγραψε:
>> 
>>
>> No. That's not how mailing lists work. Every email gets posted to all 
>> members, unless they go onto "No Mail", in which case they get no emails 
>> at all.
>>
>> You are not paying anything for the help you are receiving, except to 
>> give your own time in return to help others. We are all volunteers here, 
>> and nobody is going to force you to volunteer in return, but if everyone 
>> only received threads that they initiated, nobody would see new threads 
>> and nobody would get any answers at all.
>>
>>
>> You are right, i will set to receive them all.
>>
>> But i dont know what to do about the thing you say that i double post.
>> I use google groups i dont intentionally post to python-list too.
>> How can i avoid that and just only post to python google group?

Once you get the emails from the official mailing list, posting a reply
is straightforward.  Do a reply-all for most messages, perhaps deleting
some of the to or cc addresses depending on a specific message.  Then
trim the parts you're not responding to, and put your new remarks after
the context you are responding to.  It won't double-post.

For new messages, simply address a new message to python-list@python.org

Depending on your mail reader, you can see the messages in threads,
except for all the people who bust up the threads.  When you get to that
point, post a new thread specifying your email program and OS, and
somebody will probably volunteer to help you get it customized (though
perhaps the actual discussion for that would be offline).

For anybody else listening, the way I avoid seeing the google-groups
double-post is to automatically delete any message that's got a cc to
google-groups.  That way I only get the OTHER copy of the message.



-- 

DaveA

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Re: Obnoxious postings from Google Groups

[Mayuresh Kathe]

On Sunday 16 September 2012 09:11 PM, pandora.ko...@gmail.com wrote:

Τη Κυριακή, 16 Σεπτεμβρίου 2012 4:18:50 μ.μ. UTC+3, ο χρήστης Ben Finney έγραψε:

Νικόλαος Κούρας  writes:




Iam sorry i didnt do that on purpose and i dont know how this is done.







Iam positng via google groups using chrome, thats all i know.








It is becoming quite clear that some change has happened recently to

Google Groups that makes posts coming from there rather more obnoxious

than before. And there doesn't seem to be much its users can do except

use something else.



Using Google Groups for posting to Usenet has been a bad idea for a long

time, but now it just seems to be a sure recipe for annoying the rest of

us. Again, not something you have much control over, except to stop

using Google Groups.



If i ditch google groups what application can i use in Windows 8 to post to
this newsgroup and what newsserver too?



Thunderbird 15 as the newsgroup client and Unison Access as the news 
server (it's a paid service).


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Re: unit test strategy

[Steven D'Aprano]

On Sun, 16 Sep 2012 11:38:15 -0700, Aaron Brady wrote:


> Here is an example of some repetitive code.
> 
> for view_meth in [ dict.items, dict.keys, dict.values ]:
>   dict0= dict( ( k, None ) for k in range( 10 ) ) 
>   iter0= iter( view_meth( dict0 ) )
>   dict.__setitem__( dict0, 0, 1 )
>   next( iter0 )
>   dict.__setitem__( dict0, 10, 1 )
>   self.assertRaises( IterationError, next, iter0 )
[...]

First off, if you have any wish for this to be accepted into the standard 
library, I suggest you stick to PEP 8. Spaces on *both* sides of equals 
signs, not just one(!!!), and *no* spaces around the parenthesised 
arguments.

Secondly, this is test code. A bit of repetition is not to be concerned 
about, clarity is far more important than "Don't Repeat Yourself". The 
aim isn't to write the fastest, or most compact code, but to have good 
test coverage with tests which are *obviously* correct (rather than test 
code which has no obvious bugs, which is very different). If a test 
fails, you should be able to identify quickly what failed without running 
a debugger to identify what part of the code failed.

Thirdly, why are you writing dict.__setitem__( dict0, 0, 1 ) instead of 
dict0[0] = 1 ?


[...]
> Specifically my questions are, is the code condensed beyond legibility? 

Yes.


> Should 'chain' execute the test directly, or act as a metaprogram and
> output the test code into a 2nd file, or both?

None of the above.


> Should 'chain' create
> the iterators in a dictionary, or in the function local variables
> directly with 'exec'?

Heavens to Murgatroyd, you can't be serious.


Here's my attempt at this. Note the features:

- meaningful names (if a bit long, but that's a hazard of tests)
- distinct methods for each distinct test case
- comments explaining what the test code does
- use of subclassing


# Untested
class TestDictIteratorModificationDetection(unittest.TestCase):
"""Test that iterators to dicts will correctly detect when the
dict has been modified, and raise an exception.
"""

def create_dict(self):
return dict.fromkeys(range(10))

def testIteratorAllowed(self):
# Iterators are allowed to run if all modifications occur
# after the iterator is created but before it starts running.
d = self.create_dict()
for view in (dict.items, dict.keys, dict.values):
# Create an iterator before modifying the dict, but do not
# start iterating over it.
it = iter(view(d))
# Be careful of the order of modifications here.
del d[2]
d.pop(4)
d.popitem()
d.clear()
# Make sure we have something to iterate over.
d[1] = 1
d.update({5: 1})
d.setdefault(8, 1)
assert d  # d is non-empty.
next(it); next(it); next(it)
self.assertRaises(StopIteration, next, it)


def iterator_fails_after_modification(self, method, *args):
"""Iterators should not be able to continue running after
the dict is modified. This helper method factors out the common
code of creating a dict, an iterator to that dict, modifying the
dict, and testing that further iteration fails.

Pass an unbound dict method which modifies the dict in place, and
and arguments to that method required.
"""
d = self.create_dict()
for view in (dict.items, dict.keys, dict.values):
it = iter(view(d))
next(it)  # no exception expected here
method(d, *args)
self.assertRaises(IterationError, next, it)

def testIteratorFailsAfterSet(self):
self.iterator_fails_after_modification(dict.__setitem__, 1, 1)

def testIteratorFailsAfterDel(self):
self.iterator_fails_after_modification(dict.__delitem__, 1)

def testIteratorFailsAfterUpdate(self):
self.iterator_fails_after_modification(dict.update, {5: 1})

def testIteratorFailsAfterPop(self):
self.iterator_fails_after_modification(dict.pop, 4)

def testStartedIteratorFailsAfterPopItem(self):
self.iterator_fails_after_modification(dict.popitem)

def testStartedIteratorFailsAfterClear(self):
self.iterator_fails_after_modification(dict.clear)

def testStartedIteratorFailsAfterSetDefault(self):
self.iterator_fails_after_modification(dict.setdefault, 99, 1)



class TestDictSubclassIteratorModificationDetection(
   TestDictIteratorModificationDetection):
def create_dict(self):
class MyDict(dict):
pass
return MyDict.fromkeys(range(10))


I think I've got all the methods which can mutate a dictionary. If I 
missed any, it's easy enough to add a new test method to the class.

You are free to use the above code for your own purposes, with any 
modifications you like, with two requests:

- I would appreciate a comment in the 

Re: Decorators not worth the effort

[alex23]

On Sep 15, 6:30 am, Terry Reedy  wrote:
> > On 13Sep2012 18:58, alex23  wrote:
> > | On Sep 14, 3:54 am, Jean-Michel Pichavant 
> > | wrote:
> > | > I don't like decorators, I think they're not worth the mental effort.
> > |
> > | Because passing a function to a function is a huge cognitive burden?
>
> For parameterized decorators, there is extra cognitive burden. See below.

I do regret my initial criticism, for exactly this reason.
-- 
http://mail.python.org/mailman/listinfo/python-list

Re: Obnoxious postings from Google Groups (was: datetime issue)

[alex23]

On Sep 16, 11:18 pm, Ben Finney  wrote:
> Using Google Groups for posting to Usenet has been a bad idea for a long
> time, but now it just seems to be a sure recipe for annoying the rest of
> us. Again, not something you have much control over, except to stop
> using Google Groups.

Agreed. While it was painful but usable in its previous form, the "new
Groups" is an incomprehensible mess of pointlessness and shittery.
It's still possible to use the old theme for the time being, which
does avoid the double-up posts, but it's pretty clear Google aren't
listening to any feedback about Groups whatsoever.

I've really NFI why they bought DejaNews only to turn it into such a
broken service.
-- 
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[Roy Smith]

In article 
<6c732de0-b10f-4d40-853c-f62682970...@rg9g2000pbc.googlegroups.com>,
 alex23  wrote:

> On Sep 16, 11:18 pm, Ben Finney  wrote:
> > Using Google Groups for posting to Usenet has been a bad idea for a long
> > time, but now it just seems to be a sure recipe for annoying the rest of
> > us. Again, not something you have much control over, except to stop
> > using Google Groups.
> 
> Agreed. While it was painful but usable in its previous form, the "new
> Groups" is an incomprehensible mess of pointlessness and shittery.
> It's still possible to use the old theme for the time being, which
> does avoid the double-up posts, but it's pretty clear Google aren't
> listening to any feedback about Groups whatsoever.
> 
> I've really NFI why they bought DejaNews only to turn it into such a
> broken service.

They didn't buy the service.  They bought the data.  Well, they really 
bought both, but the data is all they wanted.
-- 
http://mail.python.org/mailman/listinfo/python-list

Python garbage collector/memory manager behaving strangely

[Jadhav, Alok]

Hi Everyone,

 

I have a simple program which reads a large file containing few million
rows, parses each row (`numpy array`) and converts into an array of
doubles (`python array`) and later writes into an `hdf5 file`. I repeat
this loop for multiple days. After reading each file, i delete all the
objects and call garbage collector.  When I run the program, First day
is parsed without any error but on the second day i get `MemoryError`. I
monitored the memory usage of my program, during first day of parsing,
memory usage is around **1.5 GB**. When the first day parsing is
finished, memory usage goes down to **50 MB**. Now when 2nd day starts
and i try to read the lines from the file I get `MemoryError`. Following
is the output of the program.

 

 

source file extracted at C:\rfadump\au\2012.08.07.txt

parsing started

current time: 2012-09-16 22:40:16.829000

50 lines parsed

100 lines parsed

150 lines parsed

200 lines parsed

250 lines parsed

300 lines parsed

350 lines parsed

400 lines parsed

450 lines parsed

500 lines parsed

parsing done.

end time is 2012-09-16 23:34:19.931000

total time elapsed 0:54:03.102000

repacking file

done

> s:\users\aaj\projects\pythonhf\rfadumptohdf.py(132)generateFiles()

-> while single_date <= self.end_date:

(Pdb) c

*** 2012-08-08 ***

source file extracted at C:\rfadump\au\2012.08.08.txt

cought an exception while generating file for day 2012-08-08.

Traceback (most recent call last):

  File "rfaDumpToHDF.py", line 175, in generateFile

lines = self.rawfile.read().split('|\n')

MemoryError

 

I am very sure that windows system task manager shows the memory usage
as **50 MB** for this process. It looks like the garbage collector or
memory manager for Python is not calculating the free memory correctly.
There should be lot of free memory but it thinks there is not enough. 

 

Any idea?

 

Thanks.

 

 

Alok Jadhav

CREDIT SUISSE AG

GAT IT Hong Kong, KVAG 67

International Commerce Centre | Hong Kong | Hong Kong

Phone +852 2101 6274 | Mobile +852 9169 7172

alok.jad...@credit-suisse.com | www.credit-suisse.com
 

 


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disclaimer: 
http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html 
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Re: Comparing strings from the back?

[alex23]

On Sep 15, 1:10 pm, Dwight Hutto  wrote:
> On Fri, Sep 14, 2012 at 6:43 PM, Prasad, Ramit
> > Since I was unsure myself if you were trying to be offensive or racist,
> > I would disagree with "everyone can know it wasn't meant as racist".
>
> If you're unsure if it was racist, you should err on the side of
> caution.

If your comments are mistakable as racism, maybe *you* should be more
cautious and *not make them*.

-- 
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Re: Obnoxious postings from Google Groups (was: datetime issue)

[alex23]

On Sep 17, 10:55 am, Roy Smith  wrote:
> They didn't buy the service.  They bought the data.  Well, they really
> bought both, but the data is all they wanted.

I thought they'd taken most of the historical data offline now too?

Either way, it was the sort of purchase-and-whither approach you
usually see Yahoo take.
-- 
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Re: Python garbage collector/memory manager behaving strangely

[Dave Angel]

On 09/16/2012 09:07 PM, Jadhav, Alok wrote:
> Hi Everyone,
>
>  
>
> I have a simple program which reads a large file containing few million
> rows, parses each row (`numpy array`) and converts into an array of
> doubles (`python array`) and later writes into an `hdf5 file`. I repeat
> this loop for multiple days. After reading each file, i delete all the
> objects and call garbage collector.  When I run the program, First day
> is parsed without any error but on the second day i get `MemoryError`. I
> monitored the memory usage of my program, during first day of parsing,
> memory usage is around **1.5 GB**. When the first day parsing is
> finished, memory usage goes down to **50 MB**. Now when 2nd day starts
> and i try to read the lines from the file I get `MemoryError`. Following
> is the output of the program.
>
>  
>
>  
>
> source file extracted at C:\rfadump\au\2012.08.07.txt
>
> parsing started
>
> current time: 2012-09-16 22:40:16.829000
>
> 50 lines parsed
>
> 100 lines parsed
>
> 150 lines parsed
>
> 200 lines parsed
>
> 250 lines parsed
>
> 300 lines parsed
>
> 350 lines parsed
>
> 400 lines parsed
>
> 450 lines parsed
>
> 500 lines parsed
>
> parsing done.
>
> end time is 2012-09-16 23:34:19.931000
>
> total time elapsed 0:54:03.102000
>
> repacking file
>
> done
>
> > s:\users\aaj\projects\pythonhf\rfadumptohdf.py(132)generateFiles()
>
> -> while single_date <= self.end_date:
>
> (Pdb) c
>
> *** 2012-08-08 ***
>
> source file extracted at C:\rfadump\au\2012.08.08.txt
>
> cought an exception while generating file for day 2012-08-08.
>
> Traceback (most recent call last):
>
>   File "rfaDumpToHDF.py", line 175, in generateFile
>
> lines = self.rawfile.read().split('|\n')
>
> MemoryError
>
>  
>
> I am very sure that windows system task manager shows the memory usage
> as **50 MB** for this process. It looks like the garbage collector or
> memory manager for Python is not calculating the free memory correctly.
> There should be lot of free memory but it thinks there is not enough. 
>
>  
>
> Any idea?
>
>  
>
> Thanks.
>
>  
>
>  
>
> Alok Jadhav
>
> CREDIT SUISSE AG
>
> GAT IT Hong Kong, KVAG 67
>
> International Commerce Centre | Hong Kong | Hong Kong
>
> Phone +852 2101 6274 | Mobile +852 9169 7172
>
> alok.jad...@credit-suisse.com | www.credit-suisse.com
>  
>
>  
>

Don't blame CPython.  You're trying to do a read() of a large file,
which will result in a single large string.  Then you split it into
lines.  Why not just read it in as lines, in which case the large string
isn't necessary.   Take a look at the readlines() function.  Chances are
that even that is unnecessary, but i can't tell without seeing more of
the code.

  lines = self.rawfile.read().split('|\n')

   lines = self.rawfile.readlines()

When a single large item is being allocated, it's not enough to have
sufficient free space, the space also has to be contiguous.  After a
program runs for a while, its space naturally gets fragmented more and
more.  it's the nature of the C runtime, and CPython is stuck with it.



-- 

DaveA

-- 
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RE: Python garbage collector/memory manager behaving strangely

[Jadhav, Alok]

Thanks Dave for clean explanation. I clearly understand what is going on
now. I still need some suggestions from you on this. 

There are 2 reasons why I was using  self.rawfile.read().split('|\n')
instead of self.rawfile.readlines()

- As you have seen, the line separator is not '\n' but its '|\n'.
Sometimes the data itself has '\n' characters in the middle of the line
and only way to find true end of the line is that previous character
should be a bar '|'. I was not able specify end of line using
readlines() function, but I could do it using split() function.
(One hack would be to readlines and combine them until I find '|\n'. is
there a cleaner way to do this?)
- Reading whole file at once and processing line by line was must
faster. Though speed is not of very important issue here but I think the
tie it took to parse complete file was reduced to one third of original
time.

Regards,
Alok


-Original Message-
From: Dave Angel [mailto:d...@davea.name] 
Sent: Monday, September 17, 2012 10:13 AM
To: Jadhav, Alok
Cc: python-list@python.org
Subject: Re: Python garbage collector/memory manager behaving strangely

On 09/16/2012 09:07 PM, Jadhav, Alok wrote:
> Hi Everyone,
>
>  
>
> I have a simple program which reads a large file containing few
million
> rows, parses each row (`numpy array`) and converts into an array of
> doubles (`python array`) and later writes into an `hdf5 file`. I
repeat
> this loop for multiple days. After reading each file, i delete all the
> objects and call garbage collector.  When I run the program, First day
> is parsed without any error but on the second day i get `MemoryError`.
I
> monitored the memory usage of my program, during first day of parsing,
> memory usage is around **1.5 GB**. When the first day parsing is
> finished, memory usage goes down to **50 MB**. Now when 2nd day starts
> and i try to read the lines from the file I get `MemoryError`.
Following
> is the output of the program.
>
>  
>
>  
>
> source file extracted at C:\rfadump\au\2012.08.07.txt
>
> parsing started
>
> current time: 2012-09-16 22:40:16.829000
>
> 50 lines parsed
>
> 100 lines parsed
>
> 150 lines parsed
>
> 200 lines parsed
>
> 250 lines parsed
>
> 300 lines parsed
>
> 350 lines parsed
>
> 400 lines parsed
>
> 450 lines parsed
>
> 500 lines parsed
>
> parsing done.
>
> end time is 2012-09-16 23:34:19.931000
>
> total time elapsed 0:54:03.102000
>
> repacking file
>
> done
>
> >
s:\users\aaj\projects\pythonhf\rfadumptohdf.py(132)generateFiles()
>
> -> while single_date <= self.end_date:
>
> (Pdb) c
>
> *** 2012-08-08 ***
>
> source file extracted at C:\rfadump\au\2012.08.08.txt
>
> cought an exception while generating file for day 2012-08-08.
>
> Traceback (most recent call last):
>
>   File "rfaDumpToHDF.py", line 175, in generateFile
>
> lines = self.rawfile.read().split('|\n')
>
> MemoryError
>
>  
>
> I am very sure that windows system task manager shows the memory usage
> as **50 MB** for this process. It looks like the garbage collector or
> memory manager for Python is not calculating the free memory
correctly.
> There should be lot of free memory but it thinks there is not enough. 
>
>  
>
> Any idea?
>
>  
>
> Thanks.
>
>  
>
>  
>
> Alok Jadhav
>
> CREDIT SUISSE AG
>
> GAT IT Hong Kong, KVAG 67
>
> International Commerce Centre | Hong Kong | Hong Kong
>
> Phone +852 2101 6274 | Mobile +852 9169 7172
>
> alok.jad...@credit-suisse.com | www.credit-suisse.com
>  
>
>  
>

Don't blame CPython.  You're trying to do a read() of a large file,
which will result in a single large string.  Then you split it into
lines.  Why not just read it in as lines, in which case the large string
isn't necessary.   Take a look at the readlines() function.  Chances are
that even that is unnecessary, but i can't tell without seeing more of
the code.

  lines = self.rawfile.read().split('|\n')

   lines = self.rawfile.readlines()

When a single large item is being allocated, it's not enough to have
sufficient free space, the space also has to be contiguous.  After a
program runs for a while, its space naturally gets fragmented more and
more.  it's the nature of the C runtime, and CPython is stuck with it.



-- 

DaveA


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RE: Python garbage collector/memory manager behaving strangely

[Jadhav, Alok]

I am thinking of calling a new subprocess which will do the memory
hungry job and then release the memory as specified in the link below

http://stackoverflow.com/questions/1316767/how-can-i-explicitly-free-mem
ory-in-python/1316799#1316799

Regards,
Alok



-Original Message-
From: Dave Angel [mailto:d...@davea.name] 
Sent: Monday, September 17, 2012 10:13 AM
To: Jadhav, Alok
Cc: python-list@python.org
Subject: Re: Python garbage collector/memory manager behaving strangely

On 09/16/2012 09:07 PM, Jadhav, Alok wrote:
> Hi Everyone,
>
>  
>
> I have a simple program which reads a large file containing few
million
> rows, parses each row (`numpy array`) and converts into an array of
> doubles (`python array`) and later writes into an `hdf5 file`. I
repeat
> this loop for multiple days. After reading each file, i delete all the
> objects and call garbage collector.  When I run the program, First day
> is parsed without any error but on the second day i get `MemoryError`.
I
> monitored the memory usage of my program, during first day of parsing,
> memory usage is around **1.5 GB**. When the first day parsing is
> finished, memory usage goes down to **50 MB**. Now when 2nd day starts
> and i try to read the lines from the file I get `MemoryError`.
Following
> is the output of the program.
>
>  
>
>  
>
> source file extracted at C:\rfadump\au\2012.08.07.txt
>
> parsing started
>
> current time: 2012-09-16 22:40:16.829000
>
> 50 lines parsed
>
> 100 lines parsed
>
> 150 lines parsed
>
> 200 lines parsed
>
> 250 lines parsed
>
> 300 lines parsed
>
> 350 lines parsed
>
> 400 lines parsed
>
> 450 lines parsed
>
> 500 lines parsed
>
> parsing done.
>
> end time is 2012-09-16 23:34:19.931000
>
> total time elapsed 0:54:03.102000
>
> repacking file
>
> done
>
> >
s:\users\aaj\projects\pythonhf\rfadumptohdf.py(132)generateFiles()
>
> -> while single_date <= self.end_date:
>
> (Pdb) c
>
> *** 2012-08-08 ***
>
> source file extracted at C:\rfadump\au\2012.08.08.txt
>
> cought an exception while generating file for day 2012-08-08.
>
> Traceback (most recent call last):
>
>   File "rfaDumpToHDF.py", line 175, in generateFile
>
> lines = self.rawfile.read().split('|\n')
>
> MemoryError
>
>  
>
> I am very sure that windows system task manager shows the memory usage
> as **50 MB** for this process. It looks like the garbage collector or
> memory manager for Python is not calculating the free memory
correctly.
> There should be lot of free memory but it thinks there is not enough. 
>
>  
>
> Any idea?
>
>  
>
> Thanks.
>
>  
>
>  
>
> Alok Jadhav
>
> CREDIT SUISSE AG
>
> GAT IT Hong Kong, KVAG 67
>
> International Commerce Centre | Hong Kong | Hong Kong
>
> Phone +852 2101 6274 | Mobile +852 9169 7172
>
> alok.jad...@credit-suisse.com | www.credit-suisse.com
>  
>
>  
>

Don't blame CPython.  You're trying to do a read() of a large file,
which will result in a single large string.  Then you split it into
lines.  Why not just read it in as lines, in which case the large string
isn't necessary.   Take a look at the readlines() function.  Chances are
that even that is unnecessary, but i can't tell without seeing more of
the code.

  lines = self.rawfile.read().split('|\n')

   lines = self.rawfile.readlines()

When a single large item is being allocated, it's not enough to have
sufficient free space, the space also has to be contiguous.  After a
program runs for a while, its space naturally gets fragmented more and
more.  it's the nature of the C runtime, and CPython is stuck with it.



-- 

DaveA


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Re: Python garbage collector/memory manager behaving strangely

[alex23]

On Sep 17, 12:32 pm, "Jadhav, Alok" 
wrote:
> - As you have seen, the line separator is not '\n' but its '|\n'.
> Sometimes the data itself has '\n' characters in the middle of the line
> and only way to find true end of the line is that previous character
> should be a bar '|'. I was not able specify end of line using
> readlines() function, but I could do it using split() function.
> (One hack would be to readlines and combine them until I find '|\n'. is
> there a cleaner way to do this?)

You can use a generator to take care of your readlines requirements:

def readlines(f):
lines = []
while "f is not empty":
line = f.readline()
if not line: break
if len(line) > 2 and line[-2:] == '|\n':
lines.append(line)
yield ''.join(lines)
lines = []
else:
lines.append(line)

> - Reading whole file at once and processing line by line was must
> faster. Though speed is not of very important issue here but I think the
> tie it took to parse complete file was reduced to one third of original
> time.

With the readlines generator above, it'll read lines from the file
until it has a complete "line" by your requirement, at which point
it'll yield it. If you don't need the entire file in memory for the
end result, you'll be able to process each "line" one at a time and
perform whatever you need against it before asking for the next.

with open(u'infile.txt','r') as infile:
for line in readlines(infile):
...

Generators are a very efficient way of processing large amounts of
data. You can chain them together very easily:

real_lines = readlines(infile)
marker_lines = (l for l in real_lines if l.startswith('#'))
every_second_marker = (l for i,l in enumerate(marker_lines) if (i
+1) % 2 == 0)
map(some_function, every_second_marker)

The real_lines generator returns your definition of a line. The
marker_lines generator filters out everything that doesn't start with
#, while every_second_marker returns only half of those. (Yes, these
could all be written as a single generator, but this is very useful
for more complex pipelines).

The big advantage of this approach is that nothing is read from the
file into memory until map is called, and given the way they're
chained together, only one of your lines should be in memory at any
given time.
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Re: Comparing strings from the back?

[Chris Angelico]

On Mon, Sep 17, 2012 at 11:11 AM, alex23  wrote:
> On Sep 15, 1:10 pm, Dwight Hutto  wrote:
>> On Fri, Sep 14, 2012 at 6:43 PM, Prasad, Ramit
>> > Since I was unsure myself if you were trying to be offensive or racist,
>> > I would disagree with "everyone can know it wasn't meant as racist".
>>
>> If you're unsure if it was racist, you should err on the side of
>> caution.
>
> If your comments are mistakable as racism, maybe *you* should be more
> cautious and *not make them*.

That applies to the most obvious examples (for instance, there's a
line in a 19th century opera that uses a six-letter word starting with
'n' to refer to a dark-skinned person - for obvious reasons, that line
is usually changed in modern performances, even though it was
descriptive and not offensive when the opera was written - like
referring to a Caucasian). However, there are many things which could
be misinterpreted as racist, and I would hate to see people leaned
hard on to make their speech entirely politically correct. Use common
sense, on both sides. Don't be offensive, and don't be offended.

ChrisA
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utcnow

[Nick the Gr33k]

Hello is there a better way of writing this:

date = ( datetime.datetime.utcnow() + datetime.timedelta(hours=3) 
).strftime( '%y-%m-%d %H:%M:%S')


something like:

date = datetime.datetime.utcnow(hours=3).strftime( '%y-%m-%d %H:%M:%S')

i prefer it if it could be written as this.

Also what about dayligh savings time?
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Re: Python garbage collector/memory manager behaving strangely

[88888 Dihedral]

alex23於 2012年9月17日星期一UTC+8上午11時25分06秒寫道：
> On Sep 17, 12:32 pm, "Jadhav, Alok" 
> 
> wrote:
> 
> > - As you have seen, the line separator is not '\n' but its '|\n'.
> 
> > Sometimes the data itself has '\n' characters in the middle of the line
> 
> > and only way to find true end of the line is that previous character
> 
> > should be a bar '|'. I was not able specify end of line using
> 
> > readlines() function, but I could do it using split() function.
> 
> > (One hack would be to readlines and combine them until I find '|\n'. is
> 
> > there a cleaner way to do this?)
> 
> 
> 
> You can use a generator to take care of your readlines requirements:
> 
> 
> 
> def readlines(f):
> 
> lines = []
> 
> while "f is not empty":
> 
> line = f.readline()
> 
> if not line: break
> 
> if len(line) > 2 and line[-2:] == '|\n':
> 
> lines.append(line)
> 
> yield ''.join(lines)
> 
> lines = []
> 
> else:
> 
> lines.append(line)
> 
> 
> 
> > - Reading whole file at once and processing line by line was must
> 
> > faster. Though speed is not of very important issue here but I think the
> 
> > tie it took to parse complete file was reduced to one third of original
> 
> > time.
> 
> 
> 
> With the readlines generator above, it'll read lines from the file
> 
> until it has a complete "line" by your requirement, at which point
> 
> it'll yield it. If you don't need the entire file in memory for the
> 
> end result, you'll be able to process each "line" one at a time and
> 
> perform whatever you need against it before asking for the next.
> 
> 
> 
> with open(u'infile.txt','r') as infile:
> 
> for line in readlines(infile):
> 
> ...
> 
> 
> 
> Generators are a very efficient way of processing large amounts of
> 
> data. You can chain them together very easily:
> 
> 
> 
> real_lines = readlines(infile)
> 
> marker_lines = (l for l in real_lines if l.startswith('#'))
> 
> every_second_marker = (l for i,l in enumerate(marker_lines) if (i
> 
> +1) % 2 == 0)
> 
> map(some_function, every_second_marker)
> 
> 
> 
> The real_lines generator returns your definition of a line. The
> 
> marker_lines generator filters out everything that doesn't start with
> 
> #, while every_second_marker returns only half of those. (Yes, these
> 
> could all be written as a single generator, but this is very useful
> 
> for more complex pipelines).
> 
> 
> 
> The big advantage of this approach is that nothing is read from the
> 
> file into memory until map is called, and given the way they're
> 
> chained together, only one of your lines should be in memory at any
> 
> given time.

The basic problem is whether the output items really need 
all lines of the input text file to be buffered to 
produce the results.


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Re: utcnow

[Joost Molenaar]

Time zones! So much fun. Looks like you're dealing with UTC offsets
yourself, which gets messy as soon as you start thinking about DST. The
good news is that there's a timezone database on most systems, which you
should almost definitely use.

Take a look at python-dateutil (pip install python-dateutil):

>>> from datetime import datetime
>>> from dateutil import tz
>>> datetime.now()
datetime.datetime(2012, 9, 17, 6, 33, 57, 158555)

This is a so-called "naive datetime", it doesn't know about timezones. On
my system, it returns a time in my local time zone. (It could have been GMT
or something else entirely.) You have to call .replace() on a "naive
datetime" to set the tzinfo member to make it a timezone-aware datetime
object:

>>> AMS = tz.gettz('Europe/Amsterdam')
>>> ATH = tz.gettz('Europe/Athens')
>>> datetime.now().replace(tzinfo=AMS).astimezone(ATH)
datetime.datetime(2012, 9, 17, 7, 37, 38, 573223,
tzinfo=tzfile('/usr/share/zoneinfo/Europe/Athens'))

Voila, it seems like you're one hour ahead of me. :-)

HTH,

Joost

On 17 September 2012 06:25, Nick the Gr33k  wrote:

> Hello is there a better way of writing this:
>
> date = ( datetime.datetime.utcnow() + datetime.timedelta(hours=3)
> ).strftime( '%y-%m-%d %H:%M:%S')
>
> something like:
>
> date = datetime.datetime.utcnow(**hours=3).strftime( '%y-%m-%d %H:%M:%S')
>
> i prefer it if it could be written as this.
>
> Also what about dayligh savings time?
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>
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Re: utcnow

[Ben Finney]

Nick the Gr33k  writes:

> Hello is there a better way of writing this:
>
> date = ( datetime.datetime.utcnow() + datetime.timedelta(hours=3)
> ).strftime( '%y-%m-%d %H:%M:%S')
>
> something like:
>
> date = datetime.datetime.utcnow(hours=3).strftime( '%y-%m-%d %H:%M:%S')
>
> i prefer it if it could be written as this.

Break long complicated statements into simpler statements. You might
need to get used to naming your intermediate results.

now = datetime.datetime.utcnow()
later = now + datetime.timedelta(hours=3)
timestamp_text = later.strftime("%Y-%m-%d %H:%M:%S")

> Also what about dayligh savings time?

What about it? What has your reading of the ‘datetime’ module
documentation taught you?

-- 
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  `\ are any good, you'll have to ram them down people's throats.” |
_o__)—Howard Aiken |
Ben Finney
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Re: Comparing strings from the back?

[alex23]

On Sep 17, 2:05 pm, Chris Angelico  wrote:
> I would hate to see people leaned
> hard on to make their speech entirely politically correct. Use common
> sense, on both sides. Don't be offensive, and don't be offended.

While I would like to agree, this would require there to be no power
disparities between the parties involved, which isn't always the case.
I hate the term "politically correct", it always seems to be used in
an eye-rolling, "what a load of nonsense" way, probably because I
believe there's at least some validity in the Sapir/Whorf hypothesis
that language dictates thought.

If Ramit's name was Barbie and e was told to "get back to your dream
home" or some other guff, it would be quite rightly viewed as sexist,
whether intentional or not. Such behaviour has been called out on this
list in the past, and I'm genuinely surprised to see so little
reaction to this.
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Re: pythonOCC examples doesn't work?

[Dwight Hutto]

>> Alan Gauld quotes, "Putting on my moderator's hat", sometimes.
>>
>>> is as you describe, a monarchy whose head but seldom exercises power;
>>
>>
>> I think it's Rossenbom(or whoever the creator of the interpreter
>> written in C is), "who says benevolent dictator for life"
>>
> [snip]
> You don't know the name of the BDFL? I'm appalled! :-)
>
I know plenty of BDFL's, including that one, but the mods are not the creator.


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David Hutto
CEO: http://www.hitwebdevelopment.com
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