Book Image

The Python Apprentice

By : Robert Smallshire, Austin Bingham
Book Image

The Python Apprentice

By: Robert Smallshire, Austin Bingham

Overview of this book

Experienced programmers want to know how to enhance their craft and we want to help them start as apprentices with Python. We know that before mastering Python you need to learn the culture and the tools to become a productive member of any Python project. Our goal with this book is to give you a practical and thorough introduction to Python programming, providing you with the insight and technical craftsmanship you need to be a productive member of any Python project. Python is a big language, and it’s not our intention with this book to cover everything there is to know. We just want to make sure that you, as the developer, know the tools, basic idioms and of course the ins and outs of the language, the standard library and other modules to be able to jump into most projects.
Table of Contents (21 chapters)
Title Page
Credits
About the Authors
www.PacktPub.com
Customer Feedback
Preface
12
Afterword – Just the Beginning

Dictionaries


We'll now return to dictionaries, which lie at the heart of many Python programs, including the Python interpreter itself. We briefly looked at literal dictionaries previously, seeing how they are delimited with curly braces and contain comma-separated key value pairs, with each pair tied together by a colon:

>>> urls = {'Google': 'http://google.com',
...         'Twitter': 'http://twitter.com',
...         'Sixty North': 'http://sixty-north.com',
...         'Microsoft': 'http://microsoft.com' }
>>>

A dictionary of URLs. The order of dictionary keys is not preserved, refer to the following diagram:

Figure 5.20: Dictionary

The values are accessible via the keys:

>>> urls['Twitter']
http://twitter.com

Since each key is associated with exactly one value, and lookup is through keys, the keys must be unique within any single dictionary. It's fine, however, to have duplicate values.

Internally, the dictionary maintains pairs of references to the key objects and...