Reading data from 2 different files and writing to a single file

inshu chauhan insideshoes at gmail.com
Wed Jan 30 14:58:32 CET 2013


On Wed, Jan 30, 2013 at 2:23 PM, Dave Angel <d at davea.name> wrote:

> On 01/30/2013 05:43 AM, inshu chauhan wrote:
>
>> On Mon, Jan 28, 2013 at 6:05 PM, Dennis Lee Bieber <wlfraed at ix.netcom.com
>> >wrote:
>>
>>  On Mon, 28 Jan 2013 14:31:31 +0100, inshu chauhan
>>> <insideshoes at gmail.com> declaimed the following in
>>> gmane.comp.python.general:
>>>
>>>  In the code below I am trying to read 2 files f1 and f2 , extract some
>>>>
>>> data
>>>
>>>> from them and then trying to write them into a single file that is 'nf'.
>>>>
>>>> import cv
>>>> f1 = open(r"Z:\modules\Feature_**Vectors_300.arff")
>>>> f2 = open(r"Z:\modules\Feature_**Vectors_300_Pclass.arff")
>>>> nf = open(r"Z:\modules\trial.arff", "w")
>>>>
>>>>
>>>> for l in f1:
>>>>      sp = l.split(",")
>>>>
>>>
>>>          If you are going to be splitting on commas, you might want to
>>> read
>>> up on the csv (comma separate values) module
>>>
>>>
>> The  csv module has many fuctions but not of much use to me and it makes
>> my
>> programme slower
>>
>>
>>>
>>>>      if len(sp)!= 12:
>>>>          continue
>>>>      else:
>>>>
>>>
>>>          Given the apparent block structure, you could drop the
>>> continue/else, and more cleanly just use
>>>
>>>
>> Yeah, Thats Right
>>
>>
>>>                  if len(sp) == 12:
>>>
>>>>          ix = sp[0].strip()
>>>>          iy = sp[1].strip()
>>>>          print ix, iy
>>>>
>>>>         for s in f2:
>>>>
>>>
>>>          It's been mentioned that the indentation is wrong here
>>>
>>>
>> I dont know why the indentation is wrong ?
>>
>
> Your for statement is not lined up with the print that precedes it.  If
> your code were really that way, you'd be getting an indentation error. So
> we assume it's because your email editor is mangling the code.  Post in
> text email, not in html.
>
>
>
>>
>>>               st = s.split(",")
>>>>
>>>>           csv module again
>>>
>>>               if len(st)!= 11:
>>>>                  continue
>>>>              else:
>>>>
>>>
>>>          I'm tempted to repeat the comment on reversing the conditional
>>> BUT
>>>
>>>                   clas = st[10].strip()
>>>>
>>>>               print ix, iy, clas
>>>>               print >> nf, ix, iy, clas
>>>>
>>>>           The indentation of the print statements is not aligned with
>>> the
>>> previous assignment -- the effect is the same however as everything
>>> under the else is executed anyway.
>>>
>>>          But as has also been mentioned, ignoring indentation, the
>>> apparent
>>> algorithm you have here is going to process every line of f2 for the
>>> first line of f1 -- and then for later lines in f1 it will find f2 is at
>>> the end of file, and do nothing. If it is supposed to process every line
>>> of f2 for each line of f1, you'll need to rewind f2.
>>>
>>>
>> For that I added 'Break' statement as suggested by Chris in above mails.
>>
>>
>>>          If you mean to match one line of f1 with one line of f2, you do
>>> not
>>> want nested loops. But now you have to define the behavior if one of the
>>> two files is correct length and the other is not? Do you skip both or
>>> read the next line from the wrong length file? And how will you handle
>>> files with different numbers of records.
>>>
>>>
>> Yes , actually my Prog was like this :
>> for l in f1:
>>      sp = l.split(",")
>>
>>      if len(sp)!= 12:
>>          continue
>>      else:
>>          ix = sp[0].strip()
>>          iy = sp[1].strip()
>>
>>
>> for s in f2:
>>
>
> This is not nested, it's back at the left margin.  Or it could be posting
> wrong because you're still posting in html, instead of plain text email.




> Yes My Initial code was not nested at the same time of no use too,  I am
> trying to use zip() now :) :) nyways..
>
>
>       st = s.split(",")
>>
>>      if len(st)!= 11:
>>          continue
>>      else:
>>          clas = st[10].strip()
>>
>>      print ix, iy, clas
>>      print >> nf, ix, iy, clas
>>      break
>>
>>
>> f1.close()
>> f2.close()
>> nf.close()
>>
>> I actually dont want nested loops but cant find another way to achieve
>> what
>> I want, But for these files I am sure that they have equal lengths, thats
>> why I am taking the risk of using nested loops.
>>
>
> You have that backwards.  Because you say you can assume they're the same
> length, you don't need the flexibility (and unreadability) of the nested
> approach.  The zip approach works great, and nested is unnecessary.
>
>
> . Can you suggest any
>
>> different way to go around this problem , which could be flexible and
>> non-errorneous ?
>>
>>
>>
>
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