CODEWITHSUNDEEP
pythonpython-3.x
SoftTimur
SoftTimur

Reputation: 5520

Simultaneous iteration over several lists

I just want to use zip and map to simultaneously iterate over 3 lists:

l0 = [0,0,0,0,0,0]
l1 = [1,2,3,4,5,6]
l2 = [2,3,4,5,6,7]

result = map(lambda x, y, z: x+y+z, zip(l0, l1, l2))

print(tuple(result))

but it returns an error:

Traceback (most recent call last):
  File "pythontest.py", line 9, in <module>
    print(tuple(result))
TypeError: <lambda>() missing 2 required positional arguments: 'y' and 'z'

Could anyone help?

Upvotes: 0

Views: 70

Answers (2)

Vasilis G.
Vasilis G.

Reputation: 7844

You could use only one argument in your lambda function, since zip creates tuples of 3 elements, and then apply the sum function:

result = map(lambda elem: sum(elem), zip(l0, l1, l2))

Upvotes: 2

Yatish Kadam
Yatish Kadam

Reputation: 472

The Problem is you are using the wrong variables... The zip returns a single element which contains the individual values.. So you need to access that by using the indices. 

l0 = [0,0,0,0,0,0]
l1 = [1,2,3,4,5,6]
l2 = [2,3,4,5,6,7]
map(lambda x: x[0]+x[1]+x[2], zip(l0, l1, l2))
Out[23]: <map at 0x7fa48232f710>
result = map(lambda x: x[0]+x[1]+x[2], zip(l0, l1, l2))

print(tuple(result))
(3, 5, 7, 9, 11, 13)

Upvotes: 3

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