Changing List Values

Question

a = [1, 2, 4]
b = a
b[2] = 2
print(a)

How is the output the first option (A)?
A. [1, 2, 2]
B. [1, 2, 4]

a = [1, 2, 4]
b = a[:]
b[2] = 2
print(a)

And how would the output here be the second option (B)?

Answer 1

In the fist example, "a" and "b" are literally the same object, so any changes made to one will reflect on the other.

In the second example, "a" and "b" have the same items, but they are different objects. This process (i.e. b = a[:]) is called shallow copying.

https://medium.com/@thawsitt/assignment-vs-shallow-copy-vs-deep-copy-in-JUMP_LINK__&&__python__&&__JUMP_LINK-f70c2f0ebd86