Compare 2 seperate csv files and write difference to a new csv file - Python 2.7

Question

I am trying to compare two csv files in python and save the difference to a third csv file in python 2.7.

import csv

f1 = open (\"olddata/file1.csv\")
oldFile1         


        

Answer 1

import csv

def read_csv_file(filename):
    res = []
    with open(filename) as f:
         for line in csv.reader(f):
               res.append(line)


oldList1 = read_csv_file("olddata/file1.csv")
oldList2 = read_csv_file("olddata/file2.csv")


difference_list = []

for a,b in zip(oldList1,oldList2):
   if a != b:
       difference_list.append(a + '\t' + b)

Eventually you have a list of items and you can just write them to file.

EDIT: In this situation, [a,b,c] vs [b,c,a] will fail. If you know that [a,b,c] vs [b,c,a] should return no difference, use the following code pls.

import csv

def read_csv_file(filename):
    res = []
    with open(filename) as f:
         for line in csv.reader(f):
               res.append(line)


oldList1 = read_csv_file("olddata/file1.csv")
oldList2 = read_csv_file("olddata/file2.csv")


difference_list = []

for a in oldList1:
  for b in oldList2:
    if a != b:
       difference_list.append(a + '\t' + b)