Python Dict from CSV IndexError

Question

I need to compare 2 CSV files and I am trying to use the @Martijn Pieters solution at Python: Comparing two CSV files and searching for similar items but I am running into an error:

IndexError: list index out of range

Here is the code I am using,

import csv
with open('filename.csv', 'rb') as a:
  indices = dict((r[2], i) for i, r in enumerate(csv.reader(a)))
  print indices

filename.csv has 10 columns and 2000 rows. I want to index column 3 that has hostnames and then match with hostnames in other .csv file

type,id,hostname,os,,,,
phy,123,server1,rhel5,,,,
vir,234,server2,rhel6,,,,

I am not sure why I am getting IndexError. Please help to fix the problem.

which is it, spaces or commas that separates your data, you had spaces a minute ago? Your code runs fine since you edited. — Padraic Cunningham, Jul 15 '14 at 20:18

score 3 · Accepted Answer · edited May 23 '17 at 11:50

You probably have empty lines at the start or end of your csv file.

I was able to reproduce this error with the following code:

import csv

with open('filename.csv', 'wb') as a:
    strng = """
type,id,hostname,os,,,,
phy,123,server1,rhel5,,,,
vir,234,server2,rhel6,,,,

"""
    a.write(strng)

with open('filename.csv', 'rb') as a:
    indices = dict((r[2], i) for i, r in enumerate(csv.reader(a)))
    print indices

However when I removed those blank lines, the code runs perfectly :

import csv

with open('filename.csv', 'wb') as a:
    strng = """type,id,hostname,os,,,,
phy,123,server1,rhel5,,,,
vir,234,server2,rhel6,,,,    
"""
    a.write(strng)

with open('filename.csv', 'rb') as a:
    indices = dict((r[2], i) for i, r in enumerate(csv.reader(a)))
    print indices

Refer to this SO Answer on how to skip blank lines in csv.

Thank you @rvraghav93! That was it, at the bottom of the file there are few lines with only one column. I removed those and it works fine now. — , Jul 15 '14 at 20:45

Python Dict from CSV IndexError

1 Answers1