Question

I want to use a ‘.’ as a delimiter, but I get an “IndexError: list index out of range” error with the code below. If I remove the delimiter portion, the code works as I want it to. Any idea why this? Many thanks in advance.

import csv

mags = csv.reader(open("mags.csv","rU"), delimiter='.')

for row in mags:

     print [item.lower() for item in [row[index] for index in (1, 0)]]

Answer 1

Perhaps there is a line that is missing the . delimiter.

To see what csv.reader is doing, add print repr(row) just before the other print-statement. That will probably reveal a line that was parsed into only zero or one fields.

If the data actually had a . delimiter in every row, your code would work fine:

>>> txt = '''\
tom.smith
ben.cohen
scott.friedman
michael.jones
'''.splitlines()
>>> import csv
>>> for row in csv.reader(txt, delimiter='.'):
        print [item.lower() for item in [row[index] for index in (1, 0)]]

['smith', 'tom']
['cohen', 'ben']
['friedman', 'scott']
['jones', 'michael']

It could be that your input data has commas for delimiters and that you want a different delimiter for the output. Here’s how:

>>> txt = '''\
tom,smith
ben,cohen
scott,friedman
michael,jones
'''.splitlines()
>>> for row in csv.reader(txt):
        print '.'.join([item.lower() for item in [row[index] for index in (1, 0)]])

smith.tom
cohen.ben
friedman.scott
jones.michael