CODEWITHSUNDEEP
python
Serhii
Serhii

Reputation: 1587

multiprocessing, pool and two lists

>>> from multiprocessing import Pool

>>> def f(x, y):
...     return x*y

>>> p = Pool(3)

>>> p.map(f, [1,2,3], [4,5,6])

And I look errors TypeError: unorderable types: list() <= int().
How to use Pool with 2 lists?

Upvotes: 4

Views: 2555

Answers (2)

damores
damores

Reputation: 2351

The problem is with the map function not the Pool object. For this case, starmap would be a good choice like this:

p.starmap(f, zip([1,2,3], [4,5,6]))

From python 3.3 starmap was added to the Pool object

Upvotes: 6

Gabriel Samain
Gabriel Samain

Reputation: 507

I don't really understand how you want to order your parameters but the idea is to have a list of tuples because your function takes 2 arguments, so something like this :

p.map(f, [(1, 4), (2, 5), (3, 6)])

and make f take a tuple as argument

def f(t):
    return t[0] * t[1]

Upvotes: 1

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