[Tutor] alphabetizing a file by lines

orbitz orbitz at ezabel.com
Mon Jul 19 08:44:31 CEST 2004

I didn't mean to imply learning how things are implemented is bad, but 
rather learn on a simple test case so you understand the basic concept, 
such as just sorting elements in a list rather than sorting them based 
on very specific needs.  That way you learn the basics of sorting, but 
then can just use builtins to accomplish a more difficult task.

Brian van den Broek wrote:

> orbitz said unto the world upon 18/07/2004 16:25:
>> Dragonfirebane seems to want to write his code in the way he has 
>> given under the guise of learning. I'm not sure if others would agree 
>> or disagree with me here, but I think doing such a thing is probably 
>> counter productive with python.
>> I'd like to hear others suggestions but here are my thoughts.
>> In python, we should generally try to avoid duplicating as much code 
>> as possible. This means making use of the standard library and 3rd 
>> party libraries where we can.  In dragonfirebane's situation he most 
>> likely wants to learn about sorting. which is fine, however I think 
>> he'd have more success if he took a simple case of say, implementing 
>> a high school level sorting algorithm on a simple list to get the 
>> idea of how sorting is done, but for something like this just using 
>> what python offers.  IMO, using large relatively complex programs to 
>> learn about relatively simplistic problems is counter productive 
>> because you spend too much time in silly details of implementation 
>> rather than focusing on what you are trying to learn.
>> Dragonfirebane at aol.com wrote:
>>> Hello all,
>>> I'm trying to write a program that alphabetizes a file by the first 
>>> letter on each line. I'm having some problems because as soon as the 
>>> program finds a letter, it looks for the next letter, ignoring 
>>> subsequent appearances of that letter. I can think of a couple ways 
>>> to fix this but none of them seem to work. The first of these would 
>>> be to add a special character to lines that have already been 
>>> alphabetized, but file.write() writes to the end of a file and i 
>>> would need to write the character at the current position in the 
>>> file. This might be circumvented by creating a file for each line 
>>> that is alphabetized, but that seems a bit extreme . . . The code is 
>>> below. Any suggestions would be appreciated. Future concerns will be 
>>> alphabetizing past the first letter.
>>> ##############
>>> def linum():
> <SNIP>
>>> Thanks in advance,
>>> Orri
>>> Email: dragonfirebane at aol.com
>>> AIM: singingxduck
>>> Programming Python for the fun of it.
>>> ------------------------------------------------------------------------ 
> Hi all,
> as I'm still learning, I doubt that it was my thoughts on this that 
> orbitz was seeking :-)
> But I spent a bit of time re-implementing a few library functions just 
> to learn how to do it (I did my own cmp() and sort() for instance). I 
> thought I learned something useful from the effort.
> I wouldn't use them again -- in fact, once they worked, I trashed 
> them. (They'd served their learning purpose.) But for learning, the 
> duplication of some of the built-in and lib functions seems almost 
> inevitable to me. Learners want to try central, basic, and fairly 
> small tasks at first. Central and basic tasks seem those likely to 
> have an implementation in Python already ;-)
> (I absolutely agree that once past learning, it would be daft not to 
> rely on the lib when what was there did what you want.)
> What I find odd about dragonfirebane's approach though is the use of 
> regular expressions to accomplish the sorting task. I felt like I was 
> learning by taking something central and re-doing it in basic building 
> blocks. By using r.e. I feel like dfb is re-doing the central and 
> fairly simple in terms of the considerably more complex and I at least 
> have doubts about the learning value of that approach. (But what do I 
> know ;-)
> Best to all,
> Brian vdB
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