Looping over list of lists, but if statement does not seem to work correctly

Question

def drawme_five(n):

    a = [['.']*n]*n
    for i in range(len(a)):
        for j in range(len(a[i])):
            if i == 0 or i == len(a)-1 or i == int(len(a)/2):
                a[i][j] = '*'
            if i < int(len(a)/2):
                a[i][0] = '*'
            elif i > int(len(a)/2):
                a[i][len(a)-1]='*'

    return a

I expected this code to give an output of a list of lists, where it with '.' and '*' in the form of number 5, but it gives me an output of all asterics. I don't know why the if statements don't work. If it works correctly, and we print one list each line, the output would be in a form of 5, for example if n = 5

. . . .

. . . . *

what in the world are you trying to accomplish? – Ironkey Oct 13 '20 at 18:33 — Ironkey, Oct 13 '20 at 18:33

score 0 · Accepted Answer · answered Oct 13 '20 at 18:36

0

If you create a 2D matrix in Python by initialising it as [['something']*n]*m, then all lists inside the main list will point to the same location. If edit even one sublist, all sublists will get edited.
Try initialising it as
lst = [['something' for i in range(m)] for j in range(n)]
to get a 2D Matrix of n x m

answered Oct 13 '20 at 18:36

Abhinav Mathur

7,791
3
10
24

ok, thanks. That seem to solve the question – Shahane Oct 13 '20 at 19:02
If so, please mark it as the accepted answer – Abhinav Mathur Oct 13 '20 at 19:03

Looping over list of lists, but if statement does not seem to work correctly

1 Answers1