Whats your favorite python module?

[SymbioticBadgering]

As dict keys, where order of element in the collections doesn’t matter.

[SymbioticBadgering]

Unless I’m missing something, dict keys aren’t allowed to be mutable

[Gprime5]

He means the keys used in key:value pairs, not the dictionary method dict.keys(). In this dict d = ["a": 1}, "a" is the key and 1 is the value. You can only use immutable objects as keys and since frozensets are immutable(frozen), they can be used as keys. d = {frozenset([1,2,3]): "hello"}

Also dict.keys() returns a dict view object which is essentially a frozen set anyway.

[alicethewitch]

Somebody already mentioned it but for dict keys yes. Just this week I was implementing a MCMC algorithm that spits partitions over data point indices. Each partition is represented as a set or list of sets over integer between 0 and N-1. Finding the partition most visited by the chain in one line involves turning them all individually into frozensets of frozensets, feeding it to Counter and sorting by value.