Python Programming for Beginners by Cannon Jason

Author:Cannon, Jason
Language: eng
Format: epub
Tags: Python
Published: 2014-08-27T16:00:00+00:00

Resources

DRY: https://en.wikipedia.org/wiki/Don%27t_repeat_yourself

Documentation for the help() built-in function: https://docs.python.org/3/library/functions.html#help

Docstring Conventions (PEP 257): http://legacy.python.org/dev/peps/pep-0257/

Chapter 5 - Lists

So far you have learned about the string, integer, float, and boolean data types. A list is a data type that holds an ordered collection of items. The items, or values, contained in a list can be various data types themselves. You can even have lists within lists.

Lists are created using comma separated values between square brackets. The format is list_name = [item_1, item_2, item_N]. To create an empty list use: list_name = []. Items in a list can be accessed by index. List indices are zero based, meaning that the first item in the list has an index of 0, the second item has an index of 1, etc. To access an item in a list using an index, enclose the index in square brackets immediately following the list name. The format is list_name[index].

animals = ['man', 'bear', 'pig'] print(animals[0]) print(animals[1]) print(animals[2])

Output:

man bear pig

Not only can you access values by index, you can also set values by index.

animals = ['man', 'bear', 'pig'] print(animals[0]) animals[0] = 'cat' print(animals[0])

Output:

man cat

You can access items starting at the end of the list by using a negative index. The -1 index represents the last item in the list, -2 represents the second to last item in the list, and so on.

animals = ['man', 'bear', 'pig'] print(animals[-1]) print(animals[-2]) print(animals[-3])

Output:

pig bear man

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