[Tutor] Diffing two files.

[Ertl, John]

Thanks,

So simple...DAAAAAA just do an equivalency on the list...no need to do sets
or step through each line. 

John 

-----Original Message-----
From: Kent Johnson [mailto:kent37 at tds.net]
Sent: Saturday, January 29, 2005 06:05
Cc: Tutor at python.org
Subject: Re: [Tutor] Diffing two files.

OK, that is clear. diffutils is probably overkill. A simple loop to
accumulate the lines of interest
should work. Here is some untested (!) code that may do what you want :-)

def getCommonPart(filePath):
   ''' Get a list containing all the lines of a file that fall between the
start and end lines.
       The returned list does not include the actual start and end lines.
       If start is not found, returns None.
       If end is not found, returns the lines after start.
   '''
   start = '-Beginning flag\n'
   end = '-Ending flag\n'
   common = None  # This will be the list of lines, also a flag of whether
start has been seen
   for line in open(filePath):
     if common is None and line == start:
       common = []
     elif line == end:
       break
     else:
       common.append(line)
   return common

# Now it's easy to compare the two files:
lines1 = getCommonPart(file1)
lines2 = getCommonPart(file2)

if lines1 != lines2:
   # Do what you need to do in case of a mismatch...
   # If you want details of the differences then you might want to use
difflib here

Kent


Ertl, John wrote:
> Kent
>
> What I need to do is find what should be common and see if it really is.
I
> have two output files...The output files will have a bunch of systems
stuff
> then the text of interest and then a bunch more systems stuff.  The
systems
> stuff may be different for each file but the text of interest will always
> have a fixed line in front of it and behind it. 
>
> The idea is to get the text of interest (using the known beginning and
> ending flags in the text) from each file and then check to make sure the
> text of interest is the same in both files.
>
> I have not done much text stuff so this is new territory for me.  I will
> take a look at difflib.
>
> Thanks again
>
> John Ertl
>
> Simplified example of a text files.
>
> Sldfsdf
> Sdfsdfsf
> Sdfsdfsdfwefs
> Sdcfasdsgerg
> Vsadgfasgdbgdfgsdf
> -Beginning flag
> This
> Text
> Should be
> The
> Same in the other file.
> -Ending flag
> Sdfsdfsdfsd
> Sdfsdfsdfasd
> Sdfsadfsdf
> Sdfsadfasdf
> Sdfsdfasd
> Sdfasdf
> s
>
>
> -----Original Message-----
> From: Kent Johnson [mailto:kent37 at tds.net]
> Sent: Friday, January 28, 2005 15:23
> Cc: Tutor at python.org
> Subject: Re: [Tutor] Diffing two files.
>
> You don't really say what you are trying to accomplish. Do you want to
> identify the common text, or
> find the pieces that differ?
>
> If the common text is always the same and you know it ahead of time, you
can
> just search the lines
> of each file to find it.
>
> If you need to identify the common part, difflib might be useful. There is
> an example on this page
> of finding matching blocks of two sequences:
> http://docs.python.org/lib/sequencematcher-examples.html
>
> In your case the sequences will be lists of lines rather than strings
(which
> are sequences of
> characters)
>
> Kent
>
> Ertl, John wrote:
>
>>All,
>>
>>I have two text files that should contain a section of text that is the
>>same.  Luckily the section of text has a defined beginning and end.  It
>>looks like the most straightforward thing would be to read the targeted
>
> text
>
>>from each file (only 50 lines or so) into lists and then compare the
>
> lists.
>
>>I would think I could use sets to find a unique list (hopefully there
>
> would
>
>>not be anything)...or I could do line by line comparison.  Any advise on
>>what is the better method.  Should I avoid the list comparison
>
> approach...is
>
>>there a built in way of comparing entire files instead of dealing
>
> explicitly
>
>>with the lines?
>>
>>Thanks,
>>
>>John Ertl
>>_______________________________________________
>>Tutor maillist  -  Tutor at python.org
>>http://mail.python.org/mailman/listinfo/tutor
>>
>
>
> _______________________________________________
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> http://mail.python.org/mailman/listinfo/tutor
>

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