Python Tutorials

Python Copy List

Copy List

You can not copy one list to another list variable by simply assigning it with an equal sign (list_1 == list_2).

In this case, list_2 is the only reference to list_1, and when you make changes to list_1, those changes automatically appear in list_2.

The copy() function in Python allows you to copy a list.

Example

colors_list = ["Red", "Blue", "Green"]

copy_colors_list = colors_list.copy()

print(copy_colors_list)

['Red', 'Blue', 'Green']

In the above example, we copy the colors list using the copy() function. In the output, you can see that the new copy colors list (copy_colors_list) matches the original colors list (colors_list).

Copy Using Import Copy

You can also import a copy module to copy the objects.

Example

import copy as cp

colors_list = ["Red", "Blue", "Green"]

copy_colors_list = cp.copy(colors_list)

print(copy_colors_list)

['Red', 'Blue', 'Green']

In the above example, we imported the copy module and copied the colors_list to a copy_colors_list.

Copy Using List Function

You can also copy the list using Python built-in list() function.

Example

colors_list = ["Red", "Blue", "Green"]

copy_colors_list = list(colors_list)

print(copy_colors_list)

['Red', 'Blue', 'Green']

In the above example, we copy the colors list using the list() function.

Verify Copy List Objects

Using the id() function, you can verify whether the list of copy objects is the same or different.

A numeric value is a return by the id() function, which is memory address of the object.

Example

colors_list = ["Red", "Blue", "Green"]

copy_colors_list_1 = colors_list
copy_colors_list_2 = list(colors_list)

print(id(colors_list), id(copy_colors_list_1))
print(id(colors_list), id(copy_colors_list_2))

4442206656 4442206656
4442206656 4442432960

As you can see in the output, assigned list objects have the same memory address, while copied list objects have different addresses.