Table of Contents
In this tutorial, we will learn about the Python List copy() method with the help of examples.
The copy() method returns a shallow copy of the list.
Example
# mixed list
prime_numbers = [2, 3, 5]
# copying a list
numbers = prime_numbers.copy()
print('Copied List:', numbers)
# Output: Copied List: [2, 3, 5]
1. Syntax of List copy()
The syntax of the copy() method is:
new_list = list.copy()
2. copy() parameters
The copy() method doesn’t take any parameters.
3. Return Value from copy()
The copy() method returns a new list. It doesn’t modify the original list.
4. Example: Copying a List
# mixed list
my_list = ['cat', 0, 6.7]
# copying a list
new_list = my_list.copy()
print('Copied List:', new_list)
Output
Copied List: ['cat', 0, 6.7]
If you modify the new_list in the above example, my_list will not be modified.
5. List copy using =
A list can be copied using the = operator. For example,
old_list = [1, 2, 3] new_list = old_list
The problem with copying lists in this way is that if you modify new_list, old_list is also modified. It is because the new list is referencing or pointing to the same old_list object.
old_list = [1, 2, 3]
# copy list using =
new_list = old_list
# add an element to list
new_list.append('a')
print('New List:', new_list)
print('Old List:', old_list)
Output
Old List: [1, 2, 3, 'a'] New List: [1, 2, 3, 'a']
However, if you need the original list unchanged when the new list is modified, you can use the copy() method.
Related tutorial: Python Shallow Copy Vs Deep Copy
6. Example: Copy List Using Slicing Syntax
# shallow copy using the slicing syntax
# mixed list
list = ['cat', 0, 6.7]
# copying a list using slicing
new_list = list[:]
# Adding an element to the new list
new_list.append('dog')
# Printing new and old list
print('Old List:', list)
print('New List:', new_list)
Output
Old List: ['cat', 0, 6.7] New List: ['cat', 0, 6.7, 'dog']
