Reading by positions plain text files

[Javier Van Dam]

Ok. I will try it and let you know. Thanks a lot!!

J

> Date: Tue, 30 Nov 2010 20:32:56 -0600
> From: python.list at tim.thechases.com
> To: javiervandam at gmail.com
> CC: python-list at python.org
> Subject: Re: Reading by positions plain text files
> 
> On 11/30/2010 08:03 PM, javivd wrote:
> > On Nov 30, 11:43 pm, Tim Harig<user... at ilthio.net>  wrote:
> >>> VARIABLE NAME      POSITION (COLUMN) IN FILE
> >>> var_name_1                 123-123
> >>> var_name_2                 124-125
> >>> var_name_3                 126-126
> >>> ..
> >>> ..
> >>> var_name_N                 512-513 (last positions)
> >>
> > and no, MRAB, it's not the similar problem (at least what i understood
> > of it). I have to associate the position this file give me with the
> > variable name this file give me for those positions.
> 
> MRAB may be referring to my reply in that thread where you can do 
> something like
> 
>    OFFSETS = 'offsets.txt'
>    offsets = {}
>    f = file(OFFSETS)
>    f.next() # throw away the headers
>    for row in f:
>      varname, rest = row.split()[:2]
>      # sanity check
>      if varname in offsets:
>        print "[%s] in %s twice?!" % (varname, OFFSETS)
>      if '-' not in rest: continue
>      start, stop = map(int, rest.split('-'))
>      offsets[varname] = slice(start, stop+1) # 0-based offsets
>      #offsets[varname] = slice(start+1, stop+2) # 1-based offsets
>    f.close()
> 
>    def do_something_with(data):
>      # your real code goes here
>      print data['var_name_2']
> 
>    for row in file('data.txt'):
>      data = dict((name, row[offsets[name]]) for name in offsets)
>      do_something_with(data)
> 
> There's additional robustness-checks I'd include if your 
> offsets-file isn't controlled by you (people send me daft data).
> 
> -tkc
> 
> 
> 
> 
 		 	   		  
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