python histogram one-liner

Question

There are many ways to write a Python program that computes a histogram.

By histogram, I mean a function that counts the occurrence of objects in an iterable

Answer 1

It's kinda cheaty to import modules for oneliners, so here's a oneliner that is O(n) and works at least as far back as Python2.4

>>> f=lambda s,d={}:([d.__setitem__(i,d.get(i,0)+1) for i in s],d)[-1]
>>> f("ABRACADABRA")
{'A': 5, 'R': 2, 'B': 2, 'C': 1, 'D': 1}

And if you think __ methods are hacky, you can always do this

>>> f=lambda s,d=lambda:0:vars(([setattr(d,i,getattr(d,i,0)+1) for i in s],d)[-1])
>>> f("ABRACADABRA")
{'A': 5, 'R': 2, 'B': 2, 'C': 1, 'D': 1}

:)

Answer 2

import pandas as pd

pd.Series(list(L)).value_counts()

Answer 3

$d{$_} += 1 for split //, 'abracadabra';