https://prefect.io
Join Slack
`from prefect import task, Flow` `from typing import Tuple` ...
# ask-community
p
from prefect import task, Flow
from typing import Tuple
@task
def double_and_triple(x: int) -> Tuple[int, int]:
return x * 2, x * 3
with Flow("This works") as flow:
a = [1,2,3]
double, triple = double_and_triple.map(x=a)
returns:
Copy code
Traceback (most recent call last):
  File "test_mult_ret.py", line 11, in <module>
    double, triple = double_and_triple.map(x=a)
  File "/home/macmenaminpe/.local/lib/python3.8/site-packages/prefect/core/task.py", line 1034, in __iter__
    raise TypeError(
TypeError: Task is not iterable. If your task returns multiple results, pass `nout` to the task decorator/constructor, or provide a `Tuple` return-type annotation to your task.
(same if:
Copy code
@task(nout=2)
a
nout is the right approach here. But it doesn't work with mapped tasks, check this open issue
p
Is the work around to just bundle your return into an object and return that? Or is there a nicer way of doing things?
Hmm.. this works, but I guess that extra 
zip_task
task might be nicer.
k
Yeah you need to bundle it as a list or dict. A 
zip_task
is not quite the right concept. The 
double_and_triple
task returns a 
Tuple
so mapping returns a 
List[Tuple]
. So if you map over 10 items, you get 10 Tuples. 
x, y = something
in Python means that iterable has 2 items. It assumed the output type is 
Tuple[List]
👍 1
86 Views
Open in Slack
PreviousNext
Powered by

Prefect Community

Bring your towel and join one of the fastest growing data communities. Welcome to our second-generation open source orchestration platform, a completely rethought approach to dataflow automation.

Powered by