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Fixed Length Record to CSV
File Handling example from a Well House Consultants training course
More on File Handling [link]

This example is described in the following article(s):
   • Handling JSON in Python (and a csv, marshall and pickle comparison) - [link]

Source code: flr Module: Y110
""" Fixed Length Record handling in Python ...

You can read from a file in Python using
        read to read a specific number of bytes
        readline to read a line
        readlines to read all the lines to a list
        xreadlines to read all the lines through a generator
(in Python 3, xreadlines becomes readlines ...)

Fixed length records tend to have differing amounts of spaces
between fields, so a regular expression of "one or more spaces" is
often a good way to split the lines up (you will need to use a
different technique if the fields contain "real" spaces as data)

You can then rejoin the lines using a space character - or something
more complex is you want to produce a CSV file as I did in the
following example, which reads a 60 character-per-record server log
file, echoes it as a series of lines to STDOUT, and writes a CSV
file called csv.txt. """

import re
space = re.compile(r"\s+")

fh = open("fixed_60.txt")
fho = open("csv.txt","w")

while (True):
        record = fh.read(60)
        if not record: break
        print record

        values = space.split(record)
        fho.write('"' + '","'.join(values) + '"\n')


""" Samples ----------------------

Echoed to the screen: 09/Jun/2010:03:30:02 OPTIONS 200 0 09/Jun/2010:03:30:02 OPTIONS 200 0 09/Jun/2010:03:30:02 OPTIONS 200 0 09/Jun/2010:03:30:04 GET 200 36003 09/Jun/2010:03:30:04 GET 200 13533 09/Jun/2010:03:30:03 GET 200 65501 09/Jun/2010:03:30:06 GET 200 7684 09/Jun/2010:03:30:06 GET 200 2826 09/Jun/2010:03:30:09 GET 200 10113 09/Jun/2010:03:30:14 GET 200 112096 09/Jun/2010:03:30:20 GET 200 12688 09/Jun/2010:03:30:19 GET 200 15501

Output file:



Learn about this subject
This module and example are covered on the following public courses:
 * Learning to program in Python
 * Python Programming
Also available on on site courses for larger groups

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Other Examples
This example comes from our "File Handling" training module. You'll find a description of the topic and some other closely related examples on the "File Handling" module index page.

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