How to convert a dictionary to a list of keys, with repeat counts given by the values?

Question

I need your help to solve a problem.

I want to convert a dictionary d = {key1:value1, key2:value2} into list= [keys1, keys1, ... (value1 times), k

Answer 1

You can use a comprehension like below:

list(chain.from_iterable(map(int, ((str(k) + ',') * v).split(',')[:-1]) for k, v in d1.items()))

Code:

from itertools import chain

d1 = {4: 1, 3: 2, 12: 2}

print(list(chain.from_iterable(map(int, ((str(k) + ',') * v).split(',')[:-1]) for k, v in d1.items())))
# [4, 3, 3, 12, 12]

To avoid all those fancy splits and map, you can go for:

[k for k, v in d1.items() for _ in range(v)]

which also outputs the desired output.