Question on List

Question

x = [[0]*2]*2
x [0][0] = 1
print (x)

Why is the output of above [[1,0], [1,0]] and not [[1,0], [0,0]]?

Answer 1

This is a reference issue:

* used with lists creates a list with has x times the content of the multiplied list in there.

Not a copy of the content - the actual content of the copied list - as references.

So you end up changing the same list, that is referred to in several places, instead of a similar one.

Instead of a longer answer (this problem and others of the sort are often asked about here), let me refer you to this:

https://code.sololearn.com/c89ejW97QsTN/?ref=app

After reading it, you should be able to figure out most or all similar problems.

Answer 2

Thanks a lot!