The reason csv doesn't support that is because variable-length lines are not really supported on most filesystems. What you should do instead is collect all the data in lists, then call zip() on them to transpose them after.

>>> l = [('Result_1', 'Result_2', 'Result_3', 'Result_4'), (1, 2, 3, 4), (5, 6, 7, 8)]
>>> zip(*l)
[('Result_1', 1, 5), ('Result_2', 2, 6), ('Result_3', 3, 7), ('Result_4', 4, 8)]

This is how I solved the problem

f1 = open ("inFile","r") # open input file for reading

with open('out.csv', 'w',newline="") as f:up # output csv file
    writer = csv.writer(f)
    with open('in.csv','r') as csvfile: # input csv file
        reader = csv.reader(csvfile, delimiter=',')
        for row in reader:  
            row[7] = f1.readline() # edit the 8th column 
            writer.writerow(row)
f1.close()   

python 2 users replace

with open('out.csv', 'w',newline="") as f:

by

with open('out.csv', 'wb') as f:

Change them to rows:

rows = zip(list1, list2, list3, list4, list5)

Then just:

import csv

with open(newfilePath, "w") as f:
    writer = csv.writer(f)
    for row in rows:
        writer.writerow(row)

With Python3, open the file in w mode:

with open('returns.csv', 'w') as f:
    writer = csv.writer(f)
    for val in daily_returns:
        writer.writerow([val])

With Python2.6+, open the file in wb mode:

with open('returns.csv', 'wb') as f:
    writer = csv.writer(f)
    for val in daily_returns:
        writer.writerow([val])