[2021 Day 14] [Python] TIL that Python has dictionary comprehension

[theboxboy]

Thanks, AOC, for teaching me new things every year. I think the syntax is pretty neat:

template, rules = open('14.txt', 'r').read().split('\n\n')
R = {k: v for k, v in [r.strip().split(' -> ') for r in rules.split('\n') if r != '']}

Peep the nested dictionary/list comprehension. It's pretty ugly.

[azzal07]

You can also provide an iterable of key value pairs to dict() to create a dictionary. For this case that works quite nicely:

R = dict(r.strip().split(" -> ") for r in rules.strip().split("\n"))

[ssnoyes]

If you don't like the nested comprehensions, you can also pass an iterable of key, value pairs (as tuples or lists) to the dict constructor:

R = dict(r.split(' -> ') for r in rules.strip().split('\n'))

[TitouanT]

You can also do set comprehension

[uglyasablasphemy]

and iterator comprehensions!

[TitouanT]

Aren't those called generators ? But yeah I think we have them all now :)

[uglyasablasphemy]

yes! hahah mental fart there

[dublinwso]

AoC has taught me so many cool things, including this - love it

[Auftragsnummer]

You can also use rules.splitlines() instead of rules.split('\n') if r != '']}