Not all popular lists functions

Question

I think it is necessary to add to course an article describing what happens if we write list2=list1. There is a lot of users questions why list2 changes if we change list1. Such questions are in challenges too.

Answer 1

Its because for list, just pure = creates an exact copy. An exact copy will copy whatever the first term is only if methods are used, not operations.
If you don't want it, create a dry copy with [:]

Answer 2

the cause is...... list2 assigned list1's value😊. it changes by list1.

Answer 3

@Pegasus thank you! I'd like to see such an explanation in the course, I think it's important for all learners

Answer 4

# you can use id() and 'is' to examine the relationships
my_list = [1, 2, 3]

# this is assignment, an additional reference to the same object

my_list_reference = my_list

print('These are identical references', my_list is my_list_reference)
print('they point to same object in memory ?', id(my_list_reference) == id(my_list))

# you can make independent objects(copies) via the constructor

my_list_copy = list(my_list)

print('these are identical refernces?', my_list_copy is my_list)
print('they point to same object in memory?', id(my_list_copy) == id(my_list))