How to cut 2nd and 3rd column out of a textfile? python

Question

I have a tab-delimited file with lines as such:

foo bar bar <tab>x y z<tab>a foo foo
...

Imagine 1,000,000 lines, with up to 200 words per line. each word on average of 5-6 characters.

To the 2nd and 3rd column, I can do this:

with open('test.txt','r') as infile:
  column23 = [i.split('\t')[1:3] for i in infile]

or i could use unix, How can i get 2nd and third column in tab delim file in bash?

import os
column23 = [i.split('\t') os.popen('cut -f 2-3 test.txt').readlines()]

Which is faster? Is there any other way to extract the 2nd and 3rd column?

Answer 1

Use neither. Unless it proves to be too slow, use the csv module, which is far more readable.

import csv
with open('test.txt','r') as infile:
    column23 = [ cols[1:3] for cols in csv.reader(infile, delimiter="\t") ]