I want to retrieve specific indexes from an iterable. That would be equivalent to:
In [7]: def f():
...: return [1,2,3,4,5]
In [8]: (_, x, _, y, _) = f()
In [9]: x, y
Out[9]: (2, 4)
But I don't want to compute the iterable multiple times or it's very long and I don't want to write too many _s
My question is purely out of curiosity and I am actually using a local variables as shown above.
EDIT:
One solution is to simply use slicing with the notation iterable[start:end:step]:
In [24]: (x, y) = f()[1:4:2]
In [25]: x, y
Out[25]: (2, 4)`
EDDIT BIS:
Using slicing works if you need to retrieve every nth elements in an iterable but if you want elements at index 2,3 and 5,6 using operator.itemgetter(2,3,5,6)(lst) seems to be a better solution:
In [8]: operator.itemgetter(2,3,5,6)(range(10))
Out[8]: (2, 3, 5, 6)
One slightly roundabout way is to use the itemgetter function from the operator module.
import operator
m = operator.itemgetter(2,3)
x, y = m([1,2,3,4,5])
The call to itemgetter creates a callable which takes an iterable L and returns L[2] and L[3].