Question

I have a nested list which contains lists filled with strings. What I am trying to do is make each list in this nest the same length as the longest available list in that nest. This sounds easy, but my attempts have failed (I am completely new to programming) and I cannot find an answered question which is relative enough to solve my problem.

First, I determine how long the longest list is:

maxSS7 = max(len(i) for i in ssValues7))

Then, I use a for loop to extend each list by a certain amount of ‘null’ if it is not the same length as the longest list:

for row in ssValues7:
    if row < len(maxSS7):
        row.extend(['null' * (len(maxSS7) - len(row))])

I am extending the row by ‘null’ * the difference between the longest list and current list. No errors occur, but unfortunately it appears to do nothing to my nested list.

Could someone please enlighten me as to my error? Any help would be greatly appreciated.

Answer 1

The problem is with the line:

if row < len(maxSS7):

You’re comparing the list row with the integer len(maxSS7). It will evaluate to False each time. Change it to:

maxLen = max(map(len, myList))
for row in myList:
    if len(row) < maxLen:
        row.extend(...)

Martijn Peters pointed another problem with your code in his answer.