Iterating through multiple values for one dict key in Python

Question

Here is an extract from one of my python functions:

d = {'ANIMAL' : ['CAT','DOG','FISH','HEDGEHOG']}
d_list = []
for key,value in d.iteritems():
    temp = [key, value]
    d_list.append(temp)

When I print d_list it currently gives me:

>>>print d_list
[['ANIMAL', ['CAT', 'DOG', 'FISH', 'HEDGEHOG']]]

How do I rewrite the function so it gives me:

>>>print d_list
[['ANIMAL', 'CAT'],['ANIMAL', 'DOG'],['ANIMAL', 'FISH'],['ANIMAL', 'HEDGEHOG']]

Answer 1

Two nested loops can do this easily -

d = {'ANIMAL' : ['CAT','DOG','FISH','HEDGEHOG']}
d_list = []
for key, values in d.iteritems():
    for value in values:
        d_list.append([key, value])

Using list comprehension -

d_list = [[k,v] for k, values in d.iteritems() for v in values]

For python 3.x, you should change iteritems to items

Answer 2

This is how I would do it. I would iterate over the value's of the key directly.

d = {'ANIMAL' : ['CAT','DOG','FISH','HEDGEHOG']}

d_list = []

for value in d['ANIMAL']:
    temp = ['ANIMAL',value]
    d_list.append(temp)

print (d_list)

Result:

[['ANIMAL', 'CAT'], ['ANIMAL', 'DOG'], ['ANIMAL', 'FISH'], ['ANIMAL', 'HEDGEHOG']]

Answer 3

You need a second loop:

d = {'ANIMAL' : ['CAT','DOG','FISH','HEDGEHOG']}
d_list = []

for key, values in d.iteritems():
    for value in values:
            temp_list=[key, value]
            d_list.append(temp)