Pythonic Idioms

I always seem to find myself having to look up the “right” way to structure a piece of logic in Python so I thought I would create a little cheatsheet for myself (and anyone else for that matter).


We can assign a single value to more than one variable.

a = b = c = d = 0
first = second = 'unknown'


I have always done explicit, separate comparisons in an if, probably because I came from a C background. Chaining comparisons together is much more natural for a single value.

if 100 >= value >= 0:
    print("value is in the right range!")

Ternary Operators

Slightly more arcane to my mind but reminiscent of ruby syntax, ternary operators work a little different from C-like languages

value = 100 if set_to_maximum else 0

In With the In Crowd

Testing if a value exists in a set of options, or for iterating through a set of values.

exists = value in {'first', 'second', 'third'}

pet_names = ['rover', 'spot', 'fluffy']

for name in pet_names:

String Placeholders

print('Happy {celebrant.age} Birthday, {} !'.format(celebrant=person)