CODEWITHSUNDEEP
pythonlistdictionarycython
John
John

Reputation: 1821

List of products of values for all keys that match in two dictionaries

I have two hash tables in the form of dictionaries. The keys map features to a list of occurrences of said features.

a_dict = {'a': [1,2], 'b': [2,], 'c': [1,3]}
b_dict = {'a': [6], 'c': [4]}

What I need is list or ideally a numpy array that contains all combinations of occurrences for two matching features. So in this case:

result = [[1,6],
          [2,6],
          [1,4],
          [3,4]]

Since this is at some point is supposed to run as fast as possible on large dicts I was hoping to use comprehensions since they are understood by cython. But they have only gotten me to here:

>>> [itertools.product(value, a_dict[key]) for key,value in b_dict.items()]
[<itertools.product object at 0x1004a2960>, <itertools.product object at 0x1004a29b0>]

Thanks for your help!

Upvotes: 2

Views: 420

Answers (1)

unutbu
unutbu

Reputation: 879919

import numpy as np
import itertools

a_dict = {'a': [1,2], 'b': [2,], 'c': [1,3]}
b_dict = {'a': [6], 'c': [4]}

print(list(itertools.chain.from_iterable(
    itertools.product(value, b_dict[key]) for key,value in a_dict.iteritems()
    if key in b_dict)))
# [(1, 6), (2, 6), (1, 4), (3, 4)]

Upvotes: 3

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