Question

I’ve been studying Python for two weeks and there’s something I want to know when reading and writing CSV file in Python.

I used def codes for output:

def csv(filename):
  f = open(filename, 'rU') 
  lines = []
  for line in f:
    lines.append(line.rstrip('\n').split(','))
f.close()
return lines

And the result from above codes looks like:

[[‘a’, ”, ”, ”, ”, ”],

[‘b’, ”, ”, ”, ”, ”],

[‘c’, ”, ”, ”, ”, ”],

[‘d’, ”, ”, ”, ”, ”],

[‘e’, ”, ”, ”, ”, ”],

[‘f’, ”, ”, ”, ”, ”],

[‘g’, ”, ”, ”, ”, ”]]

Let’s say I want to change the value of first row that contains 'a'.

What codes can I use to define the row containing a?

Answer 1

First, use built-in csv parser.

This code will define a python list of rows which contains ‘a’:

import csv
rows = csv.reader(open('yourfile.csv', 'rb'), delimiter=' ', quotechar='|')
arows = [row for row in rows if 'a' in row]