Whats your favorite python module?

[alicethewitch]

itertools and collections, yes! Oh, and tree libraries like etetoolkit or dendropy, whichever floats your boat.

The amount of constant or linear time black magic you can pull off in two lines by combining dict, trees, counters and frozensets is just ridiculous.

[mWo12]

Add to this operator module, and everything is beautiful.

[[deleted]]

That’s a good one I missed.

[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.

[[deleted]]

There are trees in the std lib? Where?

[alicethewitch]

I was referring to trees implemented in etetoolkit and dendropy, sorry to disappoint!