Python list index out of range on return value of split

Question

I\'m writing a simple script that is trying to extract the first element from the second column of a .txt input file.

import sys

if (len(sys.argv) > 1):         


        

Answer 1

When you are working with list and trying to get value at particular index, it is always safe to see in index is in the range

if len(list_of_elements) > index: 
   print list_of_elements[index]

See:

>>> list_of_elements = [1, 2, 3, 4]
>>> len(list_of_elements)
4
>>> list_of_elements[1]
2
>>> list_of_elements[4]
Traceback (most recent call last):
  File "", line 1, in 
IndexError: list index out of range
>>> 

Now you have to find out why your list did not contain as many elements as you expected

Solution:

import sys

if (len(sys.argv) > 1):
    f = open(sys.argv[1], "r")
    print "file opened"

for line in f:
    line = line.strip().strip('\n')
    # Ensure that you are not working on empty line
    if line:
        data = line.split(",") 
    # Ensure that index is not out of range
    if len(data) > 1: print data[1]

f.close()