Array Indexing: Difference between array[:] and just array? (in python)

[varinderbarmi]

Could you please help to understand the difference between the below statements:

Let matrix be a square matrix
A = [ item[:] for item in matrix ]
B = [ item for item in matrix ]

[sanjayk]

check this thread:

Doubt in Week 5 (Python Continued...) Solution for List's Problem [7:56]

b = [i[:] for i in a]. <-- This will create a new copy, b. Further changes in a or b will only effect respective list c = [i for i in a[ <-- Here elements in c point to elements in a. If you change a or c, it will effect the other. In your case, you need new copy to store your multiplication results.