How can I assign by value in python

Question

I understand that, due to the way Python works x = []; y = x; x.append(1); y will print [1]. However, the reverse, say,

z = [1,2]
temp          


        

Answer 1

Copying a list is easy ... Just slice it:

temp = z[:]

This will create a shallow copy -- mutations to elements in the list will show up in the elements in z, but not changes to temp directly.

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For more general purposes, python has a copy module that you can use:

temp = copy.copy(z)

Or, possibly:

temp = copy.deepcopy(z)

Answer 2

Why not make temp a copy of z:

>>> z = [1, 2]
>>> temp = z[:]
>>> temp[1] = 3
>>> z
[1, 2]
>>> temp
[1, 3]
>>>

[:] easily makes a shallow copy of a list.

However, you might also be interested in copy.copy and copy.deepcopy, both of which come from Python's copy module.