Re: [Tutor] Problem Stripping
Please keep your reply on the list, unless you have something private to say.
That way others can help, or learn from your questions. I've taken the liberty
of putting this back into the list.
Leam Hall wrote:
On 04/01/2012 09:40 PM, Steven D'Aprano wrote:
leam hall wrote:
Python 2.4.3 on Red Hat 5. Trying to use strip to remove characters
but it doesn't seem to work like I thought.
res = subprocess.Popen(['uname', '-a'], stdout=subprocess.PIPE)
uname = res.stdout.read().strip()
For future reference, you should identify the shortest possible amount
of code that demonstrates the problem. See also http://sscce.org/
You are asking a question about string.strip(). Where the string comes
from is irrelevant -- there's no need to use an example as complicated
as the above, when a simple string constant will do the job perfectly.
So the shortest possible amount of code to demonstrate your problem is a
single method call:
>>> 'spam ham 1:2:3 eggs'.strip(':')
'spam ham 1:2:3 eggs'
All the stuff with subprocess.Popen and reading from stout and whatnot
doesn't have anything to do with the issue at hand. It cannot shed any
light on the problem; at best it must be ignored, at worst it may
confuse the issue.
As others have already explained, strip() does not remove characters
from anywhere in the string, it strips them from the ends only.
There is also a lstrip() and rstrip() for times you only want to remove
them from the left or right side.
Steve,
How does one minimize the example code when one doesn't know the
problem? The short example seemed to work, the long one didn't. So the
options seemed to be that the long code changed the expected behavior,
the long code was transcribed incorrectly, or I misunderstood something.
At the point of asking the question I didn't know which of those was the
issue.
That's a good question. Being able to diagnose errors or unexpected behaviour
is an absolutely critical skill for a programmer. So how could you have
diagnosed this (apparent) error?
(Apart from reading the Fine Manual, of course.)
You started off by reading some data with the subprocess module. So the first
thing to do is to replace the calls
res = subprocess.Popen(['uname', '-a'], stdout=subprocess.PIPE)
uname = res.stdout.read().strip()
with a single assignment using the exact same string:
uname = 'Linux ando 2.6.18-53.el5 #1 SMP Mon Nov 12 02:22:48 EST 2007 i686
i686 i386 GNU/Linux'
(The above should be a single line; my mail client wraps it over two lines.)
Does the problem still exist? Yes:
>>> uname.strip(':') # I expect the colons to disappear.
'Linux ando 2.6.18-53.el5 #1 SMP Mon Nov 12 02:22:48 EST 2007 i686 i686 i386
GNU/Linux'
And lo, the colons don't disappear. The "problem" (as you saw it) continues.
Clearly the problem has nothing to do with the *source* of the string. (It
would be a bizarre and strange situation if it did!)
Step two: Simplify simplify simplify. Why use 85 characters when fewer than a
dozen will do? Cut out all the irrelevant bits of the string:
>>> uname = '02:22:48'
>>> uname.strip(':')
'02:22:48'
No change in the mysterious behaviour.
At this point you have your short, simple example:
>>> '02:22:48'.strip(':') # I expect '022248'
'02:22:48'
and you can ask for help. Or if you are keen to solve this yourself, you could
try different strings and see if you can work out what's going on:
>>> '0222:48'.strip(':') # maybe it works with only 1 colon?
'0222:48'
>>> '022248:'.strip(':') # or perhaps if I move the colon somewhere else?
'022248'
>>> ':02:22:48:'.strip(':') # which colons will be removed?
'02:22:48'
--
Steven
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[Tutor] New to Python programing
Hi everybody, my name is Walter I am a new beginner with no programing experience. I am using OSX Lion, and successfully installed Python version 3. I am looking for a programing guide for beginners with no programing experience. Can you please suggest me a good one to use. Thank you. Walter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] New to Python programing
I don't currently use Python 3 and don't recommend that you use it to learn with, mostly because the bulk of the docs and learning resources are Python 2.x focused and the two are not compatible. That said, here are some resources that you may find useful (particularly if you choose to learn using 2.x): Learn Python the Hard Way: http://learnpythonthehardway.org/ How to Think Like a Computer Scientist: http://openbookproject.net/thinkcs/python/english2e/ and http://python.org/doc has a wealth of info as does http://wiki.python.org/moin/BeginnersGuide/NonProgrammers hope that's helpful. On Mon, 2012-04-02 at 17:03 -0700, Walter Luna wrote: > Hi everybody, my name is Walter I am a new beginner with no programing > experience. I am using OSX Lion, and successfully installed Python version 3. > I am looking for a programing guide for beginners with no programing > experience. Can you please suggest me a good one to use. Thank you. > > Walter > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] group txt files by month
I think what I am trying to do is relatively easy but can't get my head
around how to do it.
I have a list of txt files that contain daily rainfall for many years. I
would like to produce a list that contains the year-month and the max, min
and mean of rainfall for each month.
My main question at this stage is how to group the files by each month for
each year?
They are set out like:
r20110101.txt
r20110102.txt
r20110103.txt
r20110104.txt
r20110105.txt
r20110106.txt
r20110107.txt
r20110108.txt
r20110109.txt
r20110110.txt
r20110111.txt
r20110112.txt
r20110113.txt
r20110114.txt
r20110115.txt
r20110116.txt
r20110117.txt
r20110118.txt
and so on for each day for many years.
so far I am able to open each file and calculate the max, min and mean for
each file (see below) but not sure about grouping to monthly for each year.
MainFolder=r"E:/Rainfalldata/"
outputFolder=r"E:/test/"
for (path, dirs, files) in os.walk(MainFolder):
path=path+'/'
for fname in files:
if fname.endswith('.txt'):
filename=path+fname
f=np.genfromtxt(filename, skip_header=6)
print f.max(), f.min(), f.mean()
the ideal output would be something like:
year-month max min mean
2010-12 100 0 50
2011-01 200 0 100
2011-02 50 0 25
any feedback will be greatly appreciated.
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Re: [Tutor] group txt files by month
On Tue, Apr 3, 2012 at 9:29 AM, questions anon wrote:
> I think what I am trying to do is relatively easy but can't get my head
> around how to do it.
> I have a list of txt files that contain daily rainfall for many years. I
> would like to produce a list that contains the year-month and the max, min
> and mean of rainfall for each month.
> My main question at this stage is how to group the files by each month for
> each year?
> They are set out like:
> r20110101.txt
> r20110102.txt
> r20110103.txt
> r20110104.txt
> r20110105.txt
> r20110106.txt
> r20110107.txt
> r20110108.txt
> r20110109.txt
> r20110110.txt
> r20110111.txt
> r20110112.txt
> r20110113.txt
> r20110114.txt
> r20110115.txt
> r20110116.txt
> r20110117.txt
> r20110118.txt
>
> and so on for each day for many years.
>
> so far I am able to open each file and calculate the max, min and mean for
> each file (see below) but not sure about grouping to monthly for each year.
# -
Monthwise = {}
# --
> MainFolder=r"E:/Rainfalldata/"
> outputFolder=r"E:/test/"
> for (path, dirs, files) in os.walk(MainFolder):
> path=path+'/'
> for fname in files:
> if fname.endswith('.txt'):
> filename=path+fname
> f=np.genfromtxt(filename, skip_header=6)
> print f.max(), f.min(), f.mean()
Replace the last two lines with
# --
Monthwise[fname[1:7]] = .np.genfromtxt(filename, skip_header=6)
# -
Now at the end you have a dictionary whose keys are the strings of type '201012'
and the values are the f.
You can now iterate over the sorted keys of Monthwise
and print appropriately
[Ideal output etc SNIPPED]
HTH
Asokan Pichai
"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
-- Umberto Eco
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Re: [Tutor] New to Python programing
greetings walter, and welcome to the Python family! it looks like you've got your machine all set up. hopefully installing Python 3 wasn't too difficult -- users constantly have issues with their own installs clash with the Python that's pre-installed by Apple. as far as learning Python for beginners goes, you have to decide what version to learn -- since you have both Python 2 & 3 on your system, you have a choice. if you have existing code that's written in Python 2.x, you should learn that first. if you have "no baggage," then Python 3.x is the way to go as it is the future. regardless of which you pick, you should realize: 1) once you learn one, you will learn the other as there are only seemingly minor (but backwards-incompatible differences), 2) most books and online materials are still in Python 2 although more and more Python 3 materials are becoming available. as far as books go, the best way to learn Python is by writing games. this is an approach that works both with children as well as adults. there are several excellent books that can help you with this regard: - Hello World! Computer Programming for Kids and Other Beginners by Warren Sande and Carter Sande, Manning, - Invent your Own Computer Games with Python second edition by Al Sweigart - How to Think Like a Computer Scientist by Allen B. Downey, Jeff Elkner and Chris Meyers, Green Tea Press - Python Programming for the Absolute Beginner by Michael Dawson, Course Technology i go into a bit more detail on these as well as the books shane recommends in my "Python Reading List" article (which actually describes 3 separate reading lists): http://www.informit.com/articles/article.aspx?p=1849069 as far as online resources go, try these: - How to Think Like a Computer Scientist (Downey, Elkner, Meyers) http://www.openbookproject.net/thinkcs/ - Learning to Program (Gauld) http://www.alan-g.me.uk/l2p - LiveWires Python http://www.livewires.org.uk/python/home http://pythongames.weebly.com/livewires.html - Snake Wrangling for Kids (Briggs) http://www.briggs.net.nz/snake-wrangling-for-kids.html http://code.google.com/p/swfk/ - Computer Programming is Fun! (Handy) http://www.handysoftware.com/cpif/ - Karel the Robot clone: Guido van Robot http://gvr.sf.net http://en.wikipedia.org/wiki/Guido_van_Robot - Karel the Robot clones: RUR-PLE http://rur-ple.sf.net http://en.wikipedia.org/wiki/RUR-PLE - A Byte of Python (Swaroop) http://www.swaroopch.com/notes/Python - Instant Hacking: Learning to Program with Python (Hetland) http://hetland.org/writing/instant-hacking.html hope this all helps, and again, welcome to Python!! --wesley On Mon, Apr 2, 2012 at 5:03 PM, Walter Luna wrote: > Hi everybody, my name is Walter I am a new beginner with no programing > experience. I am using OSX Lion, and successfully installed Python version 3. > I am looking for a programing guide for beginners with no programing > experience. Can you please suggest me a good one to use. Thank you. > > Walter -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "A computer never does what you want... only what you tell it." wesley chun : wescpy at gmail : @wescpy/+wescpy Python training & consulting : CyberwebConsulting.com "Core Python" books : CorePython.com Python blog: wescpy.blogspot.com ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
