Re: [Tutor] When am I ever going to use this?
On 8/1/06, Christopher Spears <[EMAIL PROTECTED]> wrote: I've been working through a tutorial:http://www.ibiblio.org/obp/thinkCSpy/index.htm.Lately, I have been learning about abstract data types(linked lists, stacks, queues, trees, etc.). While I do enjoy the challenge of creating these objects, I amnot sure what they are used for.Queues and linked lists are also used extensively inside operating systems. Process lists are a large collections of queues organized in multiple queues implemented as linked lists and stored in one array. File systems store files by accessing data blocks through linked "blocks" (not quite the same as your linked node structure) and access to the disks and the network are through queues. Trees are used less often, but still very useful. The directory structure (folders and files) on your disk are trees, the program to search your email may use a tree. Stacks are often used for network protocols and program execution (every time you call a function, you are pushing something onto a stack). How about real life uses for these structures. Queues are one of the most natural structures from social life brought into computer science. Insects, banks, highways, birds, even the lunch line in grade school used queues. Stacks are the next, with stacks of books, papers, etc. Trees are used for people's genealogies. And you might used a linked list in a treasure hunt or for footnotes and bibliographies. Even post-it notes are a form of mental linked list. I hope this helps your understanding. -Arcege-- There's so many different worlds,So many different suns.And we have just one world,But we live in different ones. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Update BLOB with odbc
It must be easier than I am making it. sql = "UPDATE sa2.outfalls SET photo_content = %s WHERE pppoint_id ='"+record[0].strip()+"';" newsql = sql%pstuff print newsql[:150] cursor.execute(newsql) __ the print newsql[:150] => "UPDATE sa2.outfalls SET photo_content = ÿØÿá*EExif . . . " and I get this error: TypeError: argument 1 must be string without null bytes, not str which sounds reasonable, but I don't know how to fix it. Is there some escape thing that I'm missing? Ron ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] latin-1 to unicode in python
Unicode?im getting this error:invalid byte sequence for encoding "UTF8": 0x92 since the db is not handling latin-1 and is set to use UTF8 how do i handle thisthanks a lot Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great rates starting at 1¢/min.___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] latin-1 to unicode in python
anil maran wrote:
> Unicode?
> im getting this error:
> invalid byte sequence for encoding "UTF8": 0x92
>
> since the db is not handling latin-1 and is set to use UTF8 how do i
> handle this
If you have a latin-1 string and you want utf-8, convert it to Unicode
and then to utf-8 using decode() and encode():
In [1]: s='\x92'
In [3]: s.decode('latin-1').encode('utf-8')
Out[3]: '\xc2\x92'
Kent
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] When am I ever going to use this?
> Lately, I have been learning about abstract data types > (linked lists, stacks, queues, trees, etc.). While I > do enjoy the challenge of creating these objects, I am > not sure what they are used for. To be honest, with the possible exception of trees, not very often! Most of these data types are taught for historic reasons. Older programminng languages like assembler, C, BASIC, Fortran, Pascal typically only had arrays(and often only single dimensioned arrays) for collecting data, and arrays were either fixed size or had to be explicitly resized in blocks of storage. Thus a whole science grew up in Computing about how to represent data more abstractly using arrays as the underpinnings. For example a linked list could be built using 2 identical arrays. One held the data and the other held the index of the next item, like this: indexintListnext 0421 1272 266-1<-- where -1 indicates end of list... which was equivalent to a list: 42,27,66 Now we can insert a member between 42 and 27 by adding an item at index 3 then modifying the next value for 42 to be 3 and setting the next value at 3 to be 1 - like this: indexintListnext 0423 1272 266-1<-- where -1 indicates end of list... 3991 All very convoluted but produced the illusion of a python like list in a language without lists. But if the language has lists built in, which almost all modern languages do, there is no real need for most of this. You can add features like priorities and auto sorting etc etc, but this is almost trivial in modern languages whereas in old languages it was a lot of work. And if the language suuppors a dictionary type ijn addition to lists, and if it can store data of moxed types, then you can implement almost any abstract data collection easily. But the concepts of abstract data types are still taught to an increasingly bewildered audience... In practice, the average Python programmer can easily simulate or replace all of the classic data structures with built in types (with the possible exception of trees) or by using a relational database - the use of which wasn't possible in the 60's, 70's and early 80's because they hadn't been invented yet! Now implementing an RDBMS as part of a solution is so trivial that there's rarely need to worry about bulding trees etc for fast searches. That may be a slightly controversial view but it reflects my personal experience of programming with Python (and Ruby, Tcl, Smalltalk etc)! Of course if you ever have to use one of the older languages then the data structure stuff instantly applies again. HTH, Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] latin-1 to unicode in python
anil maran wrote:
> In [1]: s='\x92'
>
> In [3]: s.decode('latin-1').encode('utf-8')
>
>
> Out[3]: '\xc2\x92'
>
> is this some kind of python shell, pls clarify
Yes, it's IPython.
http://ipython.scipy.org/
Kent
>
> */Kent Johnson <[EMAIL PROTECTED]>/* wrote:
>
> anil maran wrote:
> > Unicode?
> > im getting this error:
> > invalid byte sequence for encoding "UTF8": 0x92
> >
> > since the db is not handling latin-1 and is set to use UTF8 how
> do i
> > handle this
>
> If you have a latin-1 string and you want utf-8, convert it to
> Unicode
> and then to utf-8 using decode() and encode():
>
> In [1]: s='\x92'
>
> In [3]: s.decode('latin-1').encode('utf-8')
> Out[3]: '\xc2\x92'
>
> Kent
>
> ___
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
>
>
> __
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] latin-1 to unicode in python
anil maran wrote:
> how to determine
> wat encoding it is in
> for eg i m might not know it is in latin-1
This is hard. It is better by far to know what encoding your data is in.
There is no way to determine for sure what encoding it is by looking at
the data. The best you can do is rule out some encodings, and make a
best guess. Here is one way:
http://chardet.feedparser.org/
You can also try to decode the text using different encodings and use
the first one that works. This is risky because latin-1 will always work.
Finally, a non-Python method - MS Word is pretty good about guessing the
encodings of text files.
Kent
PS Please reply on list
>
> */Kent Johnson <[EMAIL PROTECTED]>/* wrote:
>
> anil maran wrote:
> > Unicode?
> > im getting this error:
> > invalid byte sequence for encoding "UTF8": 0x92
> >
> > since the db is not handling latin-1 and is set to use UTF8 how
> do i
> > handle this
>
> If you have a latin-1 string and you want utf-8, convert it to
> Unicode
> and then to utf-8 using decode() and encode():
>
> In [1]: s='\x92'
>
> In [3]: s.decode('latin-1').encode('utf-8')
> Out[3]: '\xc2\x92'
>
> Kent
>
> ___
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
>
>
>
> How low will we go? Check out Yahoo! Messenger’s low PC-to-Phone call
> rates.
>
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] latin-1 to unicode in python
anil maran wrote:
> 'ascii' codec can't encode character u'\x96' in position 213: ordinal
> not in range(128)
>
> now i m getting this error
Please show your code and the traceback and reply on list, not to me
personally.
Kent
>
> */Kent Johnson <[EMAIL PROTECTED]>/* wrote:
>
> anil maran wrote:
> > Unicode?
> > im getting this error:
> > invalid byte sequence for encoding "UTF8": 0x92
> >
> > since the db is not handling latin-1 and is set to use UTF8 how
> do i
> > handle this
>
> If you have a latin-1 string and you want utf-8, convert it to
> Unicode
> and then to utf-8 using decode() and encode():
>
> In [1]: s='\x92'
>
> In [3]: s.decode('latin-1').encode('utf-8')
> Out[3]: '\xc2\x92'
>
> Kent
>
> ___
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
>
>
>
> Do you Yahoo!?
> Get on board. You're invited
>
>
> to try the new Yahoo! Mail Beta.
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Notes on namespaces, scopes, etc
On Fri, Jul 28, 2006 at 02:36:08PM -0700, Danny Yoo wrote: > > If there were really such a thing as nested scopes/namespaces, we would > > have a function that would give us access to them, similar to the way > > that locals() and globals() give us access to the local and global > > namespace. > > It would be _convenient_ to have such a function for inspection, but it's > not a requirement. > > Here's a function that shows lexical scope in action: > > ## > >>> def pair(x, y): > ... def f(b): > ... if b: return x > ... return y > ... return f > ... > >>> p = pair(3, 4) > >>> p(True) > 3 > >>> p(False) > 4 > ## I believe that I've incorporated most, if not all, of the suggestions from those on the list, except for Danny's suggestion (above) about closures. To paraphrase "The Treasure of the Sierra Madre": "Closures? Closures? We don't got to show you no stinking closures." After all, these notes on notes and bindings were intended to beginners, not computer science students. But, I did add a link to an explanation of closures. I've also added a collection of links to related material at the end of these notes. Hopefully, if my explanation is confusing, Alan's explanation or the standard docs will pull them through. The document itself is still here: http://www.rexx.com/~dkuhlman/python_comments.html#namespaces And, thanks again for all the help. Off topic -- For those of you who need the quote: "Badges? We ain't got no badges. We don't need no badges. I don't have to show you any stinking badges!" --Gold Hat, as played by Alfonso Bedoya "The Treasure of the Sierra Madre" (1948) Dave -- Dave Kuhlman http://www.rexx.com/~dkuhlman ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] os.walk()
I'm creating a function that traverses a directory tree and prints out paths to files: #!/usr/bin/python import os, os.path, glob def traverse(base = '.'): for root,dirs,files in os.walk(base): for name in files: path = os.path.join(root, name) print path Sample output: ./gui_screenshot.jpeg ./find_items.pyc ./find_items.py ./os ./LearningToProgram/loggablebankaccount.py ./LearningToProgram/BankAccounts.pyc ./LearningToProgram/KeysApp.py ./LearningToProgram/Message.py ./LearningToProgram/Message.pyc ./LearningToProgram/a.txt ./LearningToProgram/b.txt I'm glad that the function works smoothly. I'm just wondering how os.walk works. Shouldn't I have to write a statement like this: path = os.path.join(root, dirs, name) ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Notes on namespaces, scopes, etc
Looks good Dave. Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] smtp error from cgi script
Hi, can someone help me interpret the error output
below?
I can't tell whether this is a coding error, or a
configuration error, in which case, it would be up to my host
provider.
For privacy reasons, I have changed the actual
email addresses to [EMAIL PROTECTED] and [EMAIL PROTECTED]. The first was the
recipient and the second was the sender.
Thanks in advance.
-- Rob
SMTPRecipientsRefusedPython 2.3.5:
/usr/bin/pythonWed Aug 2 20:17:33 2006
A problem occurred in a Python script. Here is the
sequence of function calls leading up to the error, in the order they
occurred.
6263 server = smtplib.SMTP(mailserver) 64 failed = server.sendmail(From, To, text) 65 server.quit()66 if failed:failed
undefined, server = , server.sendmail =
>, From =
'[EMAIL PROTECTED]',To = '[EMAIL PROTECTED]', text = 'From: [EMAIL PROTECTED]: name@domain1.net\nDa... 1 1
\n\n'
/usr/lib/python2.3/smtplib.py in
sendmail(self=, from_addr='[EMAIL PROTECTED]',
to_addrs=['[EMAIL PROTECTED]'], msg='From: name@domain2.net\nTo: name@domain1.net\nDa...1 1
\n\n', mail_options=[],
rcpt_options=[]) 685 # the server refused all our recipients 686 self.rset() 687 raise SMTPRecipientsRefused(senderrs) 688 (code,resp) = self.data(msg) 689 if code != 250:global
SMTPRecipientsRefused = ,
senderrs = {'[EMAIL PROTECTED]':
(550, 'authentication required')}
SMTPRecipientsRefused: {'[EMAIL PROTECTED]': (550, 'authentication
required')} args = ({'[EMAIL PROTECTED]': (550, 'authentication
required')},) recipients = {'[EMAIL PROTECTED]': (550, 'authentication
required')}
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
[Tutor] critique my script!
I created a function that takes a pattern and a base
path and then uses os.walk and glob to traverse
directories starting from the base path and place
files that match the glob pattern in a dictionary.
#!/usr/bin/python
import os, os.path, glob
def glob_files(pattern, base = '.'):
path_list = []
abs_base = os.path.abspath(base)
path_list.append(abs_base)
for root,dirs,files in os.walk(abs_base):
for name in dirs:
path = os.path.join(root, name)
#print path
path_list.append(path)
globbed = {}
cwd = os.getcwd()
for p in path_list:
os.chdir(p)
matched_files = glob.glob(pattern)
if matched_files != []:
globbed[p] = matched_files
os.chdir(abs_base)
os.chdir(cwd)
return globbed
Tell me what you think. This script would probably
have been easier to write with reqular expressions,
but I was determined to use glob.
___
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
