List Methods and Functions in Python
Python has some list methods and built-in functions that you can use on lists.
1. List Methods
The following is a list of Python list methods:
| Method | Description |
| append(item) | Adds an element to the end of the list -------------------------------- Example: list = ['Apple', 'Grape', 'Melon'] list.append('Mango') |
| extend(iterable) | Adds all elements of an iterable to the list -------------------------------- Example: list = ['Apple', 'Melon', 'Kiwi', 'Watermelon']; sub_list = ['Apple', 'Grapefruit']; list.extend(sub_list) |
| insert(index, item) | Adds an element at a given position of the list -------------------------------- Example: list = ['Grapefruit', 'Melon', 'Kiwi'] list.insert(1, 'Apple') |
| remove(item) | Removes the first occurrence of a given item from the list -------------------------------- Example: list = ['AAAA', 'BBBB', 'CCCC', 'BBBB', 'DDDD'] list.remove('BBBB') |
| pop([index]) | Removes the item at the specified position in the list and returns it. And pop() removes and returns the last item of the list if index omitted. -------------------------------- Example 1: list1 = ['A', 'B', 'C', 'D'] item1 = list1.pop(1) Example 2: list2 = ['A', 'B', 'C', 'D']; item2 = list2.pop() |
| clear() | Removes all elements in the list -------------------------------- Example: list = ['A', 'B', 'C', 'D'] list.clear() |
| index(item[, start[, end]]) | Returns the index of the first occurrence of a given item -------------------------------- Example: list = ['Student A', 'Student B', 'Student C', 'Student D', 'Student B'] index_1 = list.index('Student B') index_2 = list.index('Student B', 2, 5) |
| count(item) | Counts the number of occurrences of a given element in a list. -------------------------------- Example: list = [1, 2, 3, 2, 2, 3, 2, 10, 2, 1, 2] number = list.count(2) |
| sort(key=None, reverse=False) | Sorts the items in the list ascending or descending -------------------------------- Example 1: list1 = [100, 200, 4000, 200, 200, 100, 300, 500] list1.sort() Example 2: list2 = [100, 200, 4000, 200, 200, 100, 300, 500] list2.sort(reverse = True) |
| reverse() | Reverses the elements of the list in place -------------------------------- Example: list = [100, 200, 300, 400, 500, 600, 700, 800] list.reverse() |
| copy() | Returns a shallow copy of the list -------------------------------- Example: list1 = [100, 200, 300, 400, 500] list2 = list1.copy() |
2. List Functions
The following is a list of Python functions that can be used on lists:
| Function | Description |
| all() | Returns True if all items in a list are true, otherwise returns False -------------------------------- Example: all([1>2, False, 2==2, 3<2, True]) |
| any() | Returns True if any element of a given list is true, otherwise returns False -------------------------------- Example: any([1>2, False, 2==2, 3<2, False]) |
| enumerate() | Takes a list and convert it to an enumerate object -------------------------------- Example: fruits = ["Orange", "Apple", "Kiwi", "Melon", "Grapefruit"] enumerate_object = enumerate(fruits) for index, value in enumerate_object: print ("index:", index , " | value:" , value) print ('------------------------------') enumerate_object = enumerate(fruits, 2) for index, value in enumerate_object: print ("index:", index , " | value:" , value) |
| len() | Returns the length of a given list (the number of characters in a given list, including blank spaces) -------------------------------- Example: len(["Student A", "Student B", "Student C", "Student D", "Student E"]) |
| list() | Takes an iterable and returns a list -------------------------------- Example: fruits_tuple = ("Melon", "Watermelon", "Orange", "Grapefruit", "Apple") fruits_list = list(fruits_tuple) |
| max() | Finds the maximum value in a list of numbers -------------------------------- Example: max([102, 200, 100, 300, 200, 120, 400, 450]) |
| min() | Find the smallest number in a list of numbers -------------------------------- Example: min([102, 200, 100, 300, 200, 120, 400, 450]) |
| reversed() | Takes a sequence and returns a reverse iterator -------------------------------- Example: numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] reversed_iterator = reversed(numbers) reversed_numbers = list(reversed_iterator) |
| slice() | Returns a slice object representing the set of indices specified by the start, stop, and step arguments ------------------------------- Example: fruits = ["Orange", "Apple", "Kiwi", "Melon", "Grapefruit", "Watermelon"] slice_object_n = slice(4) fruits_n = fruits[slice_object_n] slice_object_m = slice(0, 2) fruits_m = fruits[slice_object_m] slice_object_p = slice(1, 5, 2) fruits_p = fruits[slice_object_p] |
| sorted() | Takes an iterable and returns a sorted list -------------------------------- Example: numbers = [2010, 2100, 1100, 1300, 2200, 1120, 1400, 2450] small_to_large_numbers = sorted(numbers) large_to_small_numbers = sorted(numbers, reverse = True) |
| sum() | Sums all numbers in a list -------------------------------- Example: sum([2010.50, 2010.00, 1200.00, 2003.00, 1230.50, 1200.50, 2450.00]) |
Reference: https://docs.python.org/3/tutorial/datastructures.html