Change specific value in CSV file via Python

Question

I need a way to change the specific value of a column of a CSV file. For example I have this CSV file:

"Ip","Sites"
"127.0.0.1",10
"127.0.0.2",23
"127.0.0.3",50

and I need to change the value 23 to 30 of the row "127.0.0.2".

I use csv library: import csv

Answer 1

This is the solution opening the csv file, changing the values in memory and then writing back the changes to disk.

r = csv.reader(open('/tmp/test.csv')) # Here your csv file
lines = list(r)

Content of lines:

[['Ip', 'Sites'],
 ['127.0.0.1', '10'],
 ['127.0.0.2', '23'],
 ['127.0.0.3', '50']]

Modifying the values:

lines[2][1] = '30'

Content of lines:

[['Ip', 'Sites'],
 ['127.0.0.1', '10'],
 ['127.0.0.2', '30'],
 ['127.0.0.3', '50']]

Now we only have to write it back to a file

writer = csv.writer(open('/tmp/output.csv', 'w'))
writer.writerows(lines)