Python 3 List Methods & Functions

List of list methods and functions available in Python 3.

List Methods

Method	Description	Examples
`append(x)`	Adds an item (`x`) to the end of the list. This is equivalent to `a[len(a):] = [x]`.	a = ["bee", "moth"] print(a) a.append("ant") print(a) Result `['bee', 'moth'] ['bee', 'moth', 'ant']`
`extend(iterable)`	Extends the list by appending all the items from the iterable. This allows you to join two lists together. This method is equivalent to `a[len(a):] = iterable`.	a = ["bee", "moth"] print(a) a.extend(["ant", "fly"]) print(a) Result `['bee', 'moth'] ['bee', 'moth', 'ant', 'fly']`
`insert(i, x)`	Inserts an item at a given position. The first argument is the index of the element before which to insert. For example, `a.insert(0, x)` inserts at the front of the list.	a = ["bee", "moth"] print(a) a.insert(0, "ant") print(a) a.insert(2, "fly") print(a) Result `['bee', 'moth'] ['ant', 'bee', 'moth'] ['ant', 'bee', 'fly', 'moth']`
`remove(x)`	Removes the first item from the list that has a value of `x`. Returns an error if there is no such item.	a = ["bee", "moth", "ant"] print(a) a.remove("moth") print(a) Result `['bee', 'moth', 'ant'] ['bee', 'ant']`
`pop([i])`	Removes the item at the given position in the list, and returns it. If no index is specified, `pop()` removes and returns the last item in the list.	# Example 1: No index specified a = ["bee", "moth", "ant"] print(a) a.pop() print(a) # Example 2: Index specified a = ["bee", "moth", "ant"] print(a) a.pop(1) print(a) Result `['bee', 'moth', 'ant'] ['bee', 'moth'] ['bee', 'moth', 'ant'] ['bee', 'ant']`
`clear()`	Removes all items from the list. Equivalent to del `a[:]`.	a = ["bee", "moth", "ant"] print(a) a.clear() print(a) Result `['bee', 'moth', 'ant'] []`
`index(x[, start[, end]])`	Returns the position of the first list item that has a value of `x`. Raises a `ValueError` if there is no such item. The optional arguments `start` and `end` are interpreted as in the slice notation and are used to limit the search to a particular subsequence of the list. The returned index is computed relative to the beginning of the full sequence rather than the start argument.	a = ["bee", "ant", "moth", "ant"] print(a.index("ant")) print(a.index("ant", 2)) Result `1 3`
`count(x)`	Returns the number of times `x` appears in the list.	a = ["bee", "ant", "moth", "ant"] print(a.count("bee")) print(a.count("ant")) print(a.count("")) Result `1 2 0`
`sort(key=None, reverse=False)`	Sorts the items of the list in place. The arguments can be used to customize the operation. `key` Specifies a function of one argument that is used to extract a comparison key from each list element. The default value is `None` (compares the elements directly). `reverse` Boolean value. If set to `True`, then the list elements are sorted as if each comparison were reversed.	a = [3,6,5,2,4,1] a.sort() print(a) a = [3,6,5,2,4,1] a.sort(reverse=True) print(a) a = ["bee", "wasp", "moth", "ant"] a.sort() print(a) a = ["bee", "wasp", "butterfly"] a.sort(key=len) print(a) a = ["bee", "wasp", "butterfly"] a.sort(key=len, reverse=True) print(a) Result `[1, 2, 3, 4, 5, 6] [6, 5, 4, 3, 2, 1] ['ant', 'bee', 'moth', 'wasp'] ['bee', 'wasp', 'butterfly'] ['butterfly', 'wasp', 'bee']`
`reverse()`	Reverses the elements of the list in place.	a = [3,6,5,2,4,1] a.reverse() print(a) a = ["bee", "wasp", "moth", "ant"] a.reverse() print(a) Result `[1, 4, 2, 5, 6, 3] ['ant', 'moth', 'wasp', 'bee']`
`copy()`	Returns a shallow copy of the list. Equivalent to `a[:]`. Use the `copy()` method when you need to update the copy without affecting the original list. If you don't use this method (eg, if you do something like `list2 = list1`), then any updates you do to `list2` will also affect `list1`. The example at the side demonstrates this.	# WITHOUT copy() a = ["bee", "wasp", "moth"] b = a b.append("ant") print(a) print(b) # WITH copy() a = ["bee", "wasp", "moth"] b = a.copy() b.append("ant") print(a) print(b) Result `['bee', 'wasp', 'moth', 'ant'] ['bee', 'wasp', 'moth', 'ant'] ['bee', 'wasp', 'moth'] ['bee', 'wasp', 'moth', 'ant']`

List Functions

The following Python functions can be used on lists.

Method	Description	Examples
`len(s)`	Returns the number of items in the list. The `len()` function can be used on any sequence (such as a string, bytes, tuple, list, or range) or collection (such as a dictionary, set, or frozen set).	a = ["bee", "moth", "ant"] print(len(a)) Result `3`
`list([iterable])`	The `list()` constructor returns a mutable sequence list of elements. The `iterable` argument is optional. You can provide any sequence or collection (such as a string, list, tuple, set, dictionary, etc). If no argument is supplied, an empty list is returned. Strictly speaking, `list([iterable])` is actually a mutable sequence type.	print(list()) print(list([])) print(list(["bee", "moth", "ant"])) print(list([["bee", "moth"], ["ant"]])) a = "bee" print(list(a)) a = ("I", "am", "a", "tuple") print(list(a)) a = {"I", "am", "a", "set"} print(list(a)) Result `[] [] ['bee', 'moth', 'ant'] [['bee', 'moth'], ['ant']] ['b', 'e', 'e'] ['I', 'am', 'a', 'tuple'] ['am', 'I', 'a', 'set']`
`max(iterable, [, key, default])` or `max(arg1, arg2, args[, key])`	Returns the largest item in an iterable (eg, list) or the largest of two or more arguments. The `key` argument specifies a one-argument ordering function like that used for `sort()`. The `default` argument specifies an object to return if the provided iterable is empty. If the iterable is empty and `default` is not provided, a `ValueError` is raised. If more than one item shares the maximum value, only the first one encountered is returned.	a = ["bee", "moth", "ant"] print(max(a)) a = ["bee", "moth", "wasp"] print(max(a)) a = [1, 2, 3, 4, 5] b = [1, 2, 3, 4] print(max(a, b)) Result `moth wasp [1, 2, 3, 4, 5]`
`min(iterable, [, key, default])` or `min(arg1, arg2, args[, key])`	Returns the smallest item in an iterable (eg, list) or the smallest of two or more arguments. The `key` argument specifies a one-argument ordering function like that used for `sort()`. The `default` argument specifies an object to return if the provided iterable is empty. If the iterable is empty and `default` is not provided, a `ValueError` is raised. If more than one item shares the minimum value, only the first one encountered is returned.	a = ["bee", "moth", "wasp"] print(min(a)) a = ["bee", "moth", "ant"] print(min(a)) a = [1, 2, 3, 4, 5] b = [1, 2, 3, 4] print(min(a, b)) Result `bee ant [1, 2, 3, 4]`
`range(stop)` or `range(start, stop[, step])`	Represents an immutable sequence of numbers and is commonly used for looping a specific number of times in `for` loops. It can be used along with `list()` to return a list of items between a given range. Strictly speaking, `range()` is actually a mutable sequence type.	print(list(range(10))) print(list(range(1,11))) print(list(range(51,56))) print(list(range(1,11,2))) Result `[0, 1, 2, 3, 4, 5, 6, 7, 8, 9] [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] [51, 52, 53, 54, 55] [1, 3, 5, 7, 9]`