Explain the difference between the "append" and "extend" methods in Python lists.

Question

Aryan Kumar · Answer

The append() and extend() methods are both used to add elements to a list in Python. However, they have different behaviors.
The append() method adds a single element to the end of a list. The length of the list itself will increase by one. For example, the following code will add the element
4 to the end of the list list1:
Python
list1 = [1, 2, 3]
list1.append(4)
print(list1)
The output of the code is:
Code snippet
[1, 2, 3, 4]
The extend() method iterates over its argument adding each element to the list, extending the list. The length of the list will increase by however many elements were in the iterable argument. For example, the following code will add the elements
5 and 6 to the end of the list list1:
Python
list1 = [1, 2, 3]
list1.extend([5, 6])
print(list1)
The output of the code is:
Code snippet
[1, 2, 3, 5, 6]
Here is a table summarizing the differences between append() and 
extend():
Feature
append()
extend()
Adds a single element
Yes
No
Adds elements from an iterable
No
Yes
Increases the list length by one
Yes
Length of iterable
Time complexity
O(1)
O(k)
Here are some examples of how append() and extend() can be used:
Python
# Append a single element to a list
list1 = [1, 2, 3]
list1.append(4)
print(list1)
# Extend a list with the elements of another list
list2 = [5, 6]
list1.extend(list2)
print(list1)
# Extend a list with the elements of a string
list1 = [1, 2, 3]
list1.extend("abc")
print(list1)

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Explain the difference between the "append" and "extend" methods in Python lists.

Steilla Mitchel

1 Answers

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Feature	`append()`	`extend()`
Adds a single element	Yes	No
Adds elements from an iterable	No	Yes
Increases the list length by one	Yes	Length of iterable
Time complexity	O(1)	O(k)