Lists
A list in Python is an ordered group of items or elements, and these list elements don't have to be of the same type. Lists are mutable objects that can change their values.
List indexes like strings starting at 0 in the beginning of list and working their way from -1 at the end.
Similar to strings, Lists operations include slicing ([] and [:]), concatenation (+), repetition (*), and membership (in).
access, update and delete list elements is like:
>>> list1 = ['programming', 'python', 1996, 2019, 0.5]
>>> print(list1[0])
programming
>>> print(list1[1:4])
['python', 1996, 2019]
>>> list1[2] = 2000
>>> print(list1[2])
2000
>>> del(list1[4])
>>> print(list1)
['programming', 'python', 2000, 2019]
Lists can have sub-lists as elements and these sub-lists may contain other sub-lists as well.
>>> persons = [["Abolfazl", 1996], ["Sarah", 1997]]
>>> name = persons[0][0]
>>> birth = persons[0][1]
>>> print("{} was born on {}".format(name, birth))
Abolfazl was born on 1996
Common List Functions
| Function | Description |
|---|---|
cmp(list1, list2) | Compares elements of both lists. |
len(list) | Gives the total length of the list. |
max(list) | Returns item from the list with max value. |
min(list) | Returns item from the list with min value. |
list(tuple) | Returns item from the list with min value. |
List Comprehensions consists of an expression followed by a for clause.
Common List Methods
| Method | Description |
|---|---|
list.append(obj) | Appends object obj to list |
list.insert(index, obj) | Inserts object obj into list at offset index |
list.count(obj) | Returns count of how many times obj occurs in list |
list.index(obj) | Returns the lowest index in list that obj appears |
list.remove(obj) | Removes object obj from list |
list.reverse() | Reverses objects of list in place |
list.sort() | Sorts objects of list in place |