What is the difference between Python's list methods append and extend?

append: Appends object at the end.

x = [1, 2, 3]

x.append([4, 5])

print (x)

gives you: [1, 2, 3, [4, 5]]
extend: Extends list by appending elements from the iterable.

x = [1, 2, 3]

x.extend([4, 5])

print (x)

gives you: [1, 2, 3, 4, 5]

4 years ago

append-adds its argument as a single element to the end of a list. The length of the list itself will increase by one.
extend-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.

4 years ago