[Tutor] Newbie: Help on comparing files

[Isr Gish]

Thanks Danny, I'll try this.

-----Original Message-----
   >From: "Danny Yoo"<dyoo at hkn.eecs.berkeley.edu>
   >Sent: 1/13/04 5:04:22 PM
   >To: "Terry Carroll"<carroll at tjc.com>
   >Cc: "tutor at python.org"<tutor at python.org>
   >Subject: Re: [Tutor] Newbie: Help on comparing files
     >
   >
   >On Tue, 13 Jan 2004, Terry Carroll wrote:
   >
   >> On Mon, 12 Jan 2004, Isr Gish wrote:
   >>
   >> > This is the code I wrote to compare the files.
   >>
   >> Isr;  I haven't tried running your code, but did you look into the
   >> difflib module to see if it did what you needed?
   >
   >
   >Hi Terry,
   >
   >difflib won't work for Isr's problem, because difflib takes the order of
   >elements into account.
   >
   >
   >
   >As a concrete example:
   >
   >###
   >>>> s1 = '''
   >... a
   >... b
   >... c
   >... '''
   >>>> s2 = '''
   >... b
   >... a
   >... c
   >... '''
   >>>> import difflib
   >>>> diff = difflib.ndiff(s1, s2)
   >>>> print ''.join(diff)
   >+
   >+ b
   >  a
   >- b-
   >  c
   >###
   >
   >
   >According to Isr's problem statement, we shouldn't get any output, because
   >all the elements in 's1' exist in 's2'.  So we can discount using
   >'difflib'.
   >
   >
   >
   >However, there's still a module in the Standard Library that should be
   >very appropriate to Isr's question: the 'sets' module:
   >
   >    http://www.python.org/doc/lib/module-sets.html
   >
   >
   >###
   >>>> from sets import Set
   >>>> t1 = 'a b c d'
   >>>> t2 = 'c b d e'
   >>>> s1 = Set(t1.split())
   >>>> s2 = Set(t2.split())
   >>>> s1
   >Set(['a', 'c', 'b', 'd'])
   >>>> s2
   >Set(['c', 'b', 'e', 'd'])
   >>>> s1 - s2
   >Set(['a'])
   >>>> s2 - s1
   >Set(['e'])
   >###
   >
   >
   >
   >Hope this clears up the situation!
   >


Thanks to all,
Isr