How to make all combinations from a dictionary in python

user_14667788 0
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I have a following dictionary:

origin = {0: [1,2], 1: [1,2,3]}

I would like to get a dictionary that makes combination key_element in value. Desired output is:

{'combo_0_1': 0, 'combo_0_2': 0, 'combo_1_1': 0, 'combo_1_2': 0, 'combo_1_3': 0}

I tried this:

output = {f"combo_{x}_{y}" : 0 for x in origin.keys() for y in origin.values()}

but it returns {'combo_0_[1, 2]': 0, 'combo_0_[1, 2, 3]': 0, 'combo_1_[1, 2]': 0, 'combo_1_[1, 2, 3]': 0} which is not what I want. How can I do it, please?

python
4 Answers

origin.values() returns all the values, which are lists. This is not what you want.

You want the elements of the current list.

output = {f"combo_{x}_{y}" : 0 for x in origin.keys() for y in origin[x]}
user_119830460

It helps to write it out as a full loop first. We can convert it to a dict comprehension after that.

You want the second part of the key to be each element of each value of origin. You can get the keys and values of origin in one outer loop, and then in the inner loop, you can loop over the elements in that value.

origin = {0: [1,2], 1: [1,2,3]}
output = {}
for key, val in origin.items():
    for elem in val:
        output[f"combo_{key}_{elem}"] = 0

Or, as a dict comprehension:

output = {f"combo_{key}_{elem}": 0 for key, val in origin.items() for elem in val}

This gives:

{'combo_0_1': 0,
 'combo_0_2': 0,
 'combo_1_1': 0,
 'combo_1_2': 0,
 'combo_1_3': 0}
user_8439530

One approach using a dictionary comprehension over dict.items:

origin = {0: [1, 2], 1: [1, 2, 3]}

res = {f"combo_{k}_{v}": 0 for k, vs in origin.items() for v in vs}
print(res)

Output

{'combo_0_1': 0, 'combo_0_2': 0, 'combo_1_1': 0, 'combo_1_2': 0, 'combo_1_3': 0}
user_40015920

Here's my solution. It generates all the permutations of your lists, and is generalized to accept longer dictionaries.

import itertools

origin = {0: [1,2], 1: [1,2,3]}
perms = list(itertools.product(*origin.values()))
output = {f"combo_"+ "_".join(map(str,p)): 0 for p in perms}
print(output)

Note: You need to map the tuples which itertools.product generates to strings to join them together to your "combo_" keys. Hope this helps!

user_138191830
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