sixtytrees - 1 month ago 5
Python Question

# Turn a list into a tuple of arguments

Python

`itertools.product()`
takes coma separated 1D lists and returns a product. I have a list of divisors of a number in a form

``````l=[[1, a1**1,a1**2,..a1**b1],[1,a2**1,..a2**b2],..[1, an**1, an**2,..an**bn]]
``````

When I pass it to itertools.product() as an argument I don't get the desired result. How can I feed this list of lists of integers to product()?

``````import itertools

print([list(x) for x in itertools.product([1,2,4],[1,3])])
#  [[1, 1], [1, 3], [2, 1], [2, 3], [4, 1], [4, 3]]  #desired

l1=[1,2,4],[1,3] #doesn't work
print([list(x) for x in itertools.product(l1)])
#[[[1, 2, 4]], [[1, 3]]]

l2=[[1,2,4],[1,3]] #doesn't work
print([list(x) for x in itertools.product(l2)])
#[[[1, 2, 4]], [[1, 3]]]
``````

You need to use `*l2` within the `product()` as `*` unwraps the list. In this case, the value of `*[[1,2,4],[1,3]]` will be `[1,2,4],[1,3]`. Here's your code:
``````l2 = [[1,2,4],[1,3]]
Please check: What does asterisk mean in python. Also read regarding `*args` and `**kwargs`, you might find it useful. Check: *args and **kwargs in python explained