Loop for each item in a list

Question

I have a dictionary:

mydict = {'item1':[1,2,3],'item2':[10,20,30]}

I want to create the cartesian product of the two so that I get a tuple of each possible pair.

output: [(1,10),(1,20),(1,30),
         (2,10),(2,20),(2,30),
         (3,10),(3,20),(3,30)]

It seems like there would be a simple way to do this so that it extends if I have three items. Kind of like a dynamic number of loops. Feels like I am missing an obvious way to do this...

Answer 1

The itertools.product() function will do this:

>>> import itertools
>>> mydict = {'item1':[1,2,3],'item2':[10,20,30]}
>>> list(itertools.product(*mydict.values()))
[(10, 1), (10, 2), (10, 3), (20, 1), (20, 2), (20, 3), (30, 1), (30, 2), (30, 3)]

If you need to control the order of the resulting tuples, you can do

itertools.product(mydict['item1'], mydict['item2'])

Answer 2

You can also brute force it using two loops

mydict = {'item1':[1,2,3],'item2':[10,20,30]}

x = []
for i in mydict['item1']:
    for j in mydict['item2']:
        x.append((i,j))

All this code does is go through all of the item in mydict['item1'], then through each item in mydict['item2'], then appends a pair of each to a new list.

It will give you this result:

[(1, 10), (1, 20), (1, 30), (2, 10), (2, 20), (2, 30), (3, 10), (3, 20), (3, 30)]