How to go through all combinations of 3 lists?

Question

I have three lists and want to call a function which takes 3 arguments with all possible combinations of values of that 3 lists.

And if a condition is met, print the 3 values of the combination.

What is the fastest and best way to do that?

Here are my three lists:

a = np.linspace(0.01,constants.pi/2,50)  
b = np.arange(20,62,2)       
c = np.arange(0.3,1.5,0.1)

And I want to call a function let's say testAllCombination(a[i],b[j],c[k]) in each iteration, and if a the value returned is > 0, print the 3 values a[i], b[j] and c[k]. Is it possible to do this in a simple way?

check out `itertools.product` in the python standard library — jeschwar, Apr 25 '19 at 18:41
Possible duplicate of [All combinations of a list of lists](https://stackoverflow.com/questions/798854/all-combinations-of-a-list-of-lists) — wwii, Apr 25 '19 at 19:01

score 0 · Answer 1 · answered Apr 25 '19 at 18:50

0

It seems you need the Cartesian product of your lists.

import itertools
list(itertools.product(a,b,c))

Note that this operation results in 50*21*12=12600 triples of items from a,b,c.

answered Apr 25 '19 at 18:50

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score 0 · Answer 2 · answered Apr 25 '19 at 18:56

if the position is fixed to (a,b,c), you may consider simple loop. Otherwise if you need to change to other combinations like (b,c,a), (c,b,a)... use itertools

a = np.linspace(0.01,3.14/2,50)  
b = np.arange(20,62,2)       
c = np.arange(0.3,1.5,0.1)

myCombination=[]

for i in a:
    for j in b:
        for k in c:
            myCombination.append((i,j,k))

print(myCombination)
for item in myCombination:
    testCondition(item)

https://docs.python.org/2/library/itertools.html

How to go through all combinations of 3 lists?

2 Answers2