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Lists

Lists are used to store multiple items in a single variable, and are created using square brackets:

B_list = ["Blossom", "Bubbles","Buttercup"]
print(B_list)

List items are changeable, ordered, and allow duplicate values. The list items are indexed, with the first item having index [0], the second item having index [1], and so on.

C_list = ["Red", "Blue", "Green", "Blue"]
print(C_list)            # duplicate
print(C_list[0])
print(C_list[1])         # ordered
C_list[2] = "Purple"     # changeable
print(C_list)

>>> %Run -c $EDITOR_CONTENT
['Red', 'Blue', 'Green', 'Blue']
Red
Blue
['Red', 'Blue', 'Purple', 'Blue']

A list can contain different data types:

A_list = ["Banana", 255, False, 3.14]
print(A_list)

>>> %Run -c $EDITOR_CONTENT
['Banana', 255, False, 3.14]

List Length

To determine how many items are in the list, use the len() function.

A_list = ["Banana", 255, False, 3.14]
print(len(A_list))

>>> %Run -c $EDITOR_CONTENT
4

Check List items

Print the second item of the list:

A_list = ["Banana", 255, False, 3.14]
print(A_list[1])

>>> %Run -c $EDITOR_CONTENT
[255]

Print the last one item of the list:

A_list = ["Banana", 255, False, 3.14]
print(A_list[-1])

>>> %Run -c $EDITOR_CONTENT
[3.14]

Print the second, third item:

A_list = ["Banana", 255, False, 3.14]
print(A_list[1:3])

>>> %Run -c $EDITOR_CONTENT
[255, False]

Change List Items

Change the second, third item:

A_list = ["Banana", 255, False, 3.14]
A_list[1:3] = [True,"Orange"]
print(A_list)

>>> %Run -c $EDITOR_CONTENT
['Banana', True, 'Orange', 3.14]

Change the second value by replacing it with two values:

A_list = ["Banana", 255, False, 3.14]
A_list[1:2] = [True,"Orange"]
print(A_list)

>>> %Run -c $EDITOR_CONTENT
['Banana', True, 'Orange', False, 3.14]

Add List Items

Using the append() method to add an item:

C_list = ["Red", "Blue", "Green"]
C_list.append("Orange")
print(C_list)

>>> %Run -c $EDITOR_CONTENT
['Red', 'Blue', 'Green', 'Orange']

Insert an item as the second position:

C_list = ["Red", "Blue", "Green"]
C_list.insert(1, "Orange")
print(C_list)

>>> %Run -c $EDITOR_CONTENT
['Red', 'Orange', 'Blue', 'Green']

Remove List Items

The remove() method removes the specified item.

C_list = ["Red", "Blue", "Green"]
C_list.remove("Blue")
print(C_list)

>>> %Run -c $EDITOR_CONTENT
['Red', 'Green']

The pop() method removes the specified index. If you do not specify the index, the pop() method removes the last item.

A_list = ["Banana", 255, False, 3.14, True,"Orange"]
A_list.pop(1)
print(A_list)
A_list.pop()
print(A_list)

>>> %Run -c $EDITOR_CONTENT
255
['Banana', False, 3.14, True, 'Orange']
'Orange'
['Banana', False, 3.14, True]

The del keyword also removes the specified index:

C_list = ["Red", "Blue", "Green"]
del C_list[1]
print(C_list)

>>> %Run -c $EDITOR_CONTENT
['Red', 'Green']

The clear() method empties the list. The list still remains, but it has no content.

C_list = ["Red", "Blue", "Green"]
C_list.clear()
print(C_list)

>>> %Run -c $EDITOR_CONTENT
[]