A shorthand way to get a unique integer mapper in Python

int_mapper_one_liner.py

# here is a tidy way to get a hashable object (such as a word) to map to a unique int in python

from collections import defaultdict
mapper = defaultdict(lambda: len(mapper))

mapper["hello"] # 0
mapper["world"]  # 1
mapper["and"]  # 2
mapper["hello"] # 0
mapper["alex"] # 3