Python provides a built-in list class that you can use to carry around almost anything. The examples here show how to create a list of numbers and then do things with the numbers in the list.
Create a list with square brackets.
abjad> my_list = [23, 7, 10, 18, 13, 20, 3, 2, 18, 9, 14, 3]
abjad> my_list
[23, 7, 10, 18, 13, 20, 3, 2, 18, 9, 14, 3]
Use len() to find the number of elements in any list.
abjad> len(my_list)
12
Use append() to add one element to a list.
abjad> my_list.append(5)
abjad> my_list
[23, 7, 10, 18, 13, 20, 3, 2, 18, 9, 14, 3, 5]
Use extend() to extend one list with the contents of another.
abjad> my_other_list = [19, 11, 4, 10, 12]
abjad> my_list.extend(my_other_list)
abjad> my_list
[23, 7, 10, 18, 13, 20, 3, 2, 18, 9, 14, 3, 5, 19, 11, 4, 10, 12]
Use reverse() to reverse the elements in a list.
abjad> my_list.reverse()
abjad> my_list
[12, 10, 4, 11, 19, 5, 3, 14, 9, 18, 2, 3, 20, 13, 18, 10, 7, 23]
You can return a single value from a list with a numeric index.
abjad> my_list[0]
12
abjad> my_list[1]
10
abjad> my_list[2]
4
You can return many values from a list with slice notation.
abjad> my_list[:4]
[12, 10, 4, 11]
More information on these and all other operations defined on the built-in Python list is available in the Python tutorial.