Python

copy() method in list

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copy() method in list - Python

This method is used to create a shallow copy of a list.

The .copy() method doesn’t take any argument.

It will return a copy of a list.

When we call this method with a list it will create a new list in the backend and iterate over the element of the original list and every element will be appended to the new list, finally it will return a new list.

It returns a shallow copy of a list which means when we modify the original list it will not affect the copied list and vice versa.

The time complexity of this method is O(n) where n is the number of element in original list

Syntax –

list.copy()

Parameters –

argument → Doesn’t take any argument

return → return a shallow copy of a list

Example –

				
					my_list=['hello', 'students', 'warm', 'welcome']
print("Original list:",my_list)
copied_list=my_list.copy()
print("Copied list:",copied_list)

# Output -
# Original list: ['hello', 'students', 'warm', 'welcome']
# Copied list: ['hello', 'students', 'warm', 'welcome']

In the above example, first we create a list with some elements and store it in my_list variable.

After creating my_list print the original list on the output screen.

Then create a copy of the original list using the .copy() method and store the copied list in the copied_list variable.

Finally, print the copied list on the output screen.

Example 2- Let’s see if modifying the original list affects the copied list or not.

				
					chambal=['bhind','morena','sheopur']
print("Orignal list:",chambal)
chambal_copy=chambal.copy()
print("Copied List:",chambal_copy)
chambal.append('gwalior')
print("Modify original list:",chambal)
print("Copied list:",chambal_copy)

# Ouput -
# Orignal list: ['bhind', 'morena', 'sheopur']
# Copied List: ['bhind', 'morena', 'sheopur']
# Modify original list: ['bhind', 'morena', 'sheopur', 'gwalior']
# Copied list: ['bhind', 'morena', 'sheopur']

Example 3- create a copy of a list without using an in-built method e.g. .copy()

				
					my_list=['hello', 'student', 'this', 'is', 'edSlash']
new_list=my_list[:]
print("Original list:",my_list)
print("Copied list:",new_list)

# Output -
# Original list: ['hello', 'student', 'this', 'is', 'edSlash']
# Copied list: ['hello', 'student', 'this', 'is', 'edSlash']

Example 4-

				
					lst=[10,20,30,40,50]
lst1=[]
for i in lst:
	lst1.append(i)
print("Original list:",lst)
print("Modified list:",lst1)

# Output -
# Original list: [10, 20, 30, 40, 50]
# Modified list: [10, 20, 30, 40, 50]

Example 5-

				
					my_list=[2,4,6,8,10,12,14,16]
my_list1=my_list
print("Original list:",my_list)
print("Copied list:"my_list1)
my_list.append(18)
print("\nModified original list:",my_list)
print("Copied list:",my_list1)

# Output -
# Original list: [2, 4, 6, 8, 10, 12, 14, 16]
# Copied list: [2, 4, 6, 8, 10, 12, 14, 16]

# Modified original list: [2, 4, 6, 8, 10, 12, 14, 16, 18]
# Copied list: [2, 4, 6, 8, 10, 12, 14, 16, 18]

In the above example, you can see that when we modify the original list it modifies the copied list as well.

It is because we do not create a copy of the original list instead of creating a copy we create another reference of the original list object.

In this situation, if we modify any list the changes will affect both the lists.

Python

copy() method in list

copy() method in list - Python

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