Difference between append vs. extend list methods in Python?

Question

What's the difference between the list methods `append()` and `extend()`?

Answer 1

In the extend() method you are extending the list by concatenating another list. For example

x=[1,2]

x.extend([4,5])

will result in x being [1,2,4,5]. This is the same as saying

x=[1,2]

x+=[4,5]

However, with append() you are appending the object passed as an element in the list. Therefore the code

x=[1,2]

x.append([4,5])

will result in [1,2,[4,5]]. This is because you appended a list into the first list. In summary the extend() method will extend a list by joining two lists. The append() method appends the object passed as the last element in the list. I hope that helps.