If coding tutorials with math examples are the bane of your existence, keep reading. This series uses relatable examples like dogs and cats.
Lists
A list is a collection which is ordered and changeable and there may be duplicate items.
Creating a List
# creating a list with a builtin function
list_name = list('list item 1', 'list item 2', 'list item 3')
# creating a list with brackets
another_list_name = ['list item 1', 'list item 2', 'list item 3']
# you can create an empty list like this
list = []
Accessing list items using indexing
| cat | dog | mouse | cheese | lemon | road |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| -6 | -5 | -4 | -3 | -2 | -1 |
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road']
print(things[0])
>>>cat
print(things[-2])
>>>lemon
Changing Lists
Lists are mutable, or modifiable.
Add via Index
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
things[0] = 'chair' # adds 'chair' to the beginning of list, at index 0
print(things) # returns newly modified list
>>>['chair', 'cat', 'dog', 'mouse', 'cheese', 'lemon', 'road']
Add to end
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
things.append = 'chair' # adds 'chair' to the end of list
print(things) # returns newly modified list
>>>['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road', 'chair']
Check
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
does_exist = 'banana' in things # sees if 'banana' is in the list
print(does_exist)
>>>True
does_exist = 'lime' in things # sees if 'lime' is in the list
print(does_exist)
>>>False
Insert
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
things.insert('pie', 1) # adds 'pie' at index 1
print(things)
>>>'cat', 'pie', 'dog', 'mouse', 'cheese', 'lemon', 'road'
Remove
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
things.remove('mouse') # removes 'mouse', regardless of index
print(things)
>>>'cat', 'dog', 'cheese', 'lemon', 'road'
Pop
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
things.pop(-2) # removes item referenced by index
print(things)
>>>'cat', 'dog', 'mouse', 'cheese', 'road'
Delete
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
del things[0] # deletes item referenced by index
print(things)
>>>'dog', 'mouse', 'cheese', 'lemon', 'road'
Clear
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'] # our list
things.clear()
print(things) # nothing will show because you've cleared all items from the list
>>>
Joining
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road']
more_things = ["table", "book", "blanket"]
new_list = things + more_things # combines both lists in the order written
print(new_list)
>>>'cat', 'dog', 'mouse', 'cheese', 'lemon', 'road', "table", "book", "blanket"
newer_list = more_things + things
print(newer_list)
>>>"table", "book", "blanket", 'cat', 'dog', 'mouse', 'cheese', 'lemon', 'road'
Counting
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road']
print(things.count())
>>>6
Reversing
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road']
things.reverse() # flip the order of the list
print(things)
>>>'road', 'lemon', 'cheese', 'mouse', 'dog', 'cat'
Sorting
things = ['cat', 'dog', 'mouse', 'cheese', 'lemon', 'road']
things.sort() # alphanumeric order
print(things)
>>>'cat', 'cheese', 'dog', 'lemon', 'mouse', 'road'
things.sort(reverse=True) # backwards
print(things)
>>>'road', 'mouse', 'lemon', 'dog', 'cheese', 'cat'
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