dicts.md

dicts [Readability]

dict.get()

What is this?

Normally one can access keys of a dict using the dict["key"] syntax, however if the key is nonexistent, it will throw a KeyError which if not appropriately handled, will crash the program.

Not pythonic

something = {'a': 1, 'b': 2}
if 'a' in something:
    print(something['a'])
something['c']
# KeyError as 'c' doesn't exist.

Pythonic

Instead, what you can do is use the .get() method. This will simply return None if the key is not found and you no longer need to check if a key is in the dict beforehand.

>>> print(something.get('a'))
1
>>> print(something.get('c'))
None

collections.defaultdict

This is another improvement to the standard dict and is discussed in collections

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References

[1] Python docs -- dict.get()

Books that mention this topic

[2] Python Tricks: A Buffet of Awesome Python Features by Dan Bader
[3] Effective Python: 90 Specific Ways to Write Better Python by Brett Slatkin
[4] Python Cookbook, Third Edition by David Beazley and Brian K. Jones
[5] Writing Idiomatic Python 3 by Jeff Knupp
[6] The Little Book of Python Anti-Patterns by QuantifiedCode