2

I have a dictionary of lists. I want to generate all combinations of those lists and return those combinations as a list of dictionaries with the correct key and value pair mappings.

I have achieved this so far by deploying the below code, but I want to be explicit about the key and value pair mappings throughout the process, rather than relying the enumeration approach below. I am concerned given that the dictionary is not ordered that the enumeration approach might be open to not mapping the key value pairs correctly somehow. In any case, I am looking for the most pythonic way to achieve the result.

import itertools

dct_lst = {'Apple':[3,5,7],'Pear':[5,2],'Orange':[10],'Banana':[7,10],'Lemon':[5,7,9,2,1]}

combs = itertools.product(*(dct_lst[key] for key in dct_lst.keys()))

lst_dct = []
for comb in combs:
    dct = {}
    for j,key in enumerate(dct_lst.keys()):
        dct[key] = comb[j]
    lst_dct.append(dct)

lst_dct

[{'Apple': 3, 'Banana': 7, 'Lemon': 5, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 7, 'Lemon': 7, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 7, 'Lemon': 9, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 7, 'Lemon': 2, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 7, 'Lemon': 1, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 10, 'Lemon': 5, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 10, 'Lemon': 7, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 10, 'Lemon': 9, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 10, 'Lemon': 2, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 10, 'Lemon': 1, 'Orange': 10, 'Pear': 5},
 {'Apple': 3, 'Banana': 7, 'Lemon': 5, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 7, 'Lemon': 7, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 7, 'Lemon': 9, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 7, 'Lemon': 2, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 7, 'Lemon': 1, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 10, 'Lemon': 5, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 10, 'Lemon': 7, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 10, 'Lemon': 9, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 10, 'Lemon': 2, 'Orange': 10, 'Pear': 2},
 {'Apple': 3, 'Banana': 10, 'Lemon': 1, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 7, 'Lemon': 5, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 7, 'Lemon': 7, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 7, 'Lemon': 9, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 7, 'Lemon': 2, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 7, 'Lemon': 1, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 10, 'Lemon': 5, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 10, 'Lemon': 7, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 10, 'Lemon': 9, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 10, 'Lemon': 2, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 10, 'Lemon': 1, 'Orange': 10, 'Pear': 5},
 {'Apple': 5, 'Banana': 7, 'Lemon': 5, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 7, 'Lemon': 7, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 7, 'Lemon': 9, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 7, 'Lemon': 2, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 7, 'Lemon': 1, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 10, 'Lemon': 5, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 10, 'Lemon': 7, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 10, 'Lemon': 9, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 10, 'Lemon': 2, 'Orange': 10, 'Pear': 2},
 {'Apple': 5, 'Banana': 10, 'Lemon': 1, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 7, 'Lemon': 5, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 7, 'Lemon': 7, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 7, 'Lemon': 9, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 7, 'Lemon': 2, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 7, 'Lemon': 1, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 10, 'Lemon': 5, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 10, 'Lemon': 7, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 10, 'Lemon': 9, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 10, 'Lemon': 2, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 10, 'Lemon': 1, 'Orange': 10, 'Pear': 5},
 {'Apple': 7, 'Banana': 7, 'Lemon': 5, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 7, 'Lemon': 7, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 7, 'Lemon': 9, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 7, 'Lemon': 2, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 7, 'Lemon': 1, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 10, 'Lemon': 5, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 10, 'Lemon': 7, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 10, 'Lemon': 9, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 10, 'Lemon': 2, 'Orange': 10, 'Pear': 2},
 {'Apple': 7, 'Banana': 10, 'Lemon': 1, 'Orange': 10, 'Pear': 2}]

The result is as expected. Though, I am interested in the most robust pythonic way to achieve this result.

benvc
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agftrading
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  • Does this answer your question? [Cartesian product of a dictionary of lists](https://stackoverflow.com/questions/5228158/cartesian-product-of-a-dictionary-of-lists) – Georgy Dec 10 '20 at 11:45

3 Answers3

2

You can repeat the key along with the values to build a list of items:

>>> import itertools
>>> dct_lst = {'Apple':[3,5,7],'Pear':[5,2],'Orange':[10],'Banana':[7,10],'Lemon':[5,7,9,2,1]}
>>> L = [[(k, v) for v in vs] for k, vs in dct_lst.items()]
>>> L
[[('Apple', 3), ('Apple', 5), ('Apple', 7)], [('Pear', 5), ('Pear', 2)], [('Orange', 10)], [('Banana', 7), ('Banana', 10)], [('Lemon', 5), ('Lemon', 7), ('Lemon', 9), ('Lemon', 2), ('Lemon', 1)]]

And use itertools.product to create all the combinations:

>>> list (itertools.product(*L))
[(('Apple', 3), ('Pear', 5), ('Orange', 10), ('Banana', 7), ('Lemon', 5)), (('Apple', 3), ('Pear', 5), ('Orange', 10), ('Banana', 7), ('Lemon', 7)), (('Apple', 3), ('Pear', 5), ('Orange', 10), ('Banana', 7), ('Lemon', 9)), ..., (('Apple', 7), ('Pear', 2), ('Orange', 10), ('Banana', 7), ('Lemon', 2)), (('Apple', 7), ('Pear', 2), ('Orange', 10), ('Banana', 7), ('Lemon', 1)), (('Apple', 7), ('Pear', 2), ('Orange', 10), ('Banana', 10), ('Lemon', 5)), (('Apple', 7), ('Pear', 2), ('Orange', 10), ('Banana', 10), ('Lemon', 7)), (('Apple', 7), ('Pear', 2), ('Orange', 10), ('Banana', 10), ('Lemon', 9)), (('Apple', 7), ('Pear', 2), ('Orange', 10), ('Banana', 10), ('Lemon', 2)), (('Apple', 7), ('Pear', 2), ('Orange', 10), ('Banana', 10), ('Lemon', 1))]

The output is made of tuples, but it's easy to create dicts:

>>> list(map(dict, itertools.product(*L)))
[{'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 5}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 7}, ..., {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 1}]
jferard
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  • I was torn between which answer to accept of the three from jferard, Adam.Er8 and benvc (I have upvoted all). This answer does seem to provide the fastest calculation, but the answer from benvc seems ever so slightly more straightforward to me. Much appreciated though and shall let the upvotes from others continue to see their determination! Thanks. – agftrading Jul 10 '19 at 14:15
1

you can use ChianMap to help merge the dicts at the end.

try this:

from itertools import product
from collections import ChainMap

dct_lst = {'Apple':[3,5,7],'Pear':[5,2],'Orange':[10],'Banana':[7,10],'Lemon':[5,7,9,2,1]}

flat_dicts = [[{key: val} for val in lst] for key, lst in dct_lst.items()]
lst_dct = list(map(lambda d: dict(ChainMap(*d)), product(*flat_dicts)))

print(lst_dct)
Adam.Er8
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1

You could use itertools.product on just the values of the dict and then dict(zip(...)) the keys and values together to output a list of dicts.

from itertools import product

d = {'Apple':[3,5,7],'Pear':[5,2],'Orange':[10],'Banana':[7,10],'Lemon':[5,7,9,2,1]}

l = [dict(zip(d.keys(), vals)) for vals in product(*d.values())]
print(l)
# [{'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 5}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 7}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 9}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 2}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 1}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 5}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 7}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 9}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 2}, {'Apple': 3, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 1}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 5}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 7}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 9}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 2}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 1}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 5}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 7}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 9}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 2}, {'Apple': 3, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 1}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 5}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 7}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 9}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 2}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 1}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 5}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 7}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 9}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 2}, {'Apple': 5, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 1}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 5}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 7}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 9}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 2}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 1}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 5}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 7}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 9}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 2}, {'Apple': 5, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 1}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 5}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 7}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 9}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 2}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 7, 'Lemon': 1}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 5}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 7}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 9}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 2}, {'Apple': 7, 'Pear': 5, 'Orange': 10, 'Banana': 10, 'Lemon': 1}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 5}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 7}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 9}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 2}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 7, 'Lemon': 1}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 5}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 7}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 9}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 2}, {'Apple': 7, 'Pear': 2, 'Orange': 10, 'Banana': 10, 'Lemon': 1}]
benvc
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