python - Convert dictionary into list with length based on values

Question

I have a dictionary

d = {1: 3, 5: 6, 10: 2}

I want to convert it to a list that holds the keys of the dictionary. Each key should be repeated as many times as its associated value.

I've written this code that does the job:

d = {1: 3, 5: 6, 10: 2}
l = []
for i in d:
    for j in range(d[i]):
        l.append(i)
l.sort()
print(l)

Output:

[1, 1, 1, 5, 5, 5, 5, 5, 5, 10, 10]

But I would like it to be a list comprehension. How can this be done?

Answer 1

You can do it using a list comprehension:

[i for i in d for j in range(d[i])]

yields:

[1, 1, 1, 10, 10, 5, 5, 5, 5, 5, 5]

You can sort it again to get the list you were looking for.