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Sourcery rule id: dict-literal


Replace dict() with {}


x = dict()


x = {}


The most concise and Pythonic way to create a dictionary is to use the {} notation.

This fits in with the way we create dictionaries with items, saving a bit of mental energy that might be taken up with thinking about two different ways of creating dicts.

x = {"first": "thing"}

Doing things this way has the added advantage of being a nice little performance improvement.

Here are the timings before and after the change:

$ python3 -m timeit "x = dict()"
5000000 loops, best of 5: 69.8 nsec per loop
$ python3 -m timeit "x = {}"
20000000 loops, best of 5: 29.4 nsec per loop

Similar reasoning and performance results hold for replacing list() with [].