Why do '*' vs list comprehension when making list of lists work differently?

Question

My purpose was to make 2D list by *

list2 = [[False]*2]*3 #[[False,False],[False,False],[False,False]]
list3 = [[False]*2 for _ in range(3)] #same as list2
list2[0][0] = True # [[True, False], [True, False], [True, False]]
list3[0][0] = True # [[True, False], [False, False], [False, False]]

list3 works well but list2 doesn't. list2 is affected by 'x' of list2[z][x].

What happened?

list2 is working as shallow copy & list3 is working as deep copy — Harsha Biyani, Dec 30 '20 at 07:05
yes, i think you're right. thanks! and the referenced question also was perfect — goguma, Dec 30 '20 at 07:16

score 0 · Answer 1 · answered Dec 30 '20 at 07:13

0

* operator concats the list and makes same replica or reference of the list so change made at one place will get replicated at all places whereas for _ range(3) will evaluate one by one hence making just one change at position list[0][0]

answered Dec 30 '20 at 07:13

think-maths

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Why do '*' vs list comprehension when making list of lists work differently?

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