Combining map with zip through lambda

Question

I'm trying to write a function for adding 2D vectors. I'm trying to combine the map() function, getting a list using the zip() function (which will zip 2 tuples).

This is the code:

a = (1, 2)
b = (3, 4)
c = list(map(lambda x, y: x+y, list(zip(a, b))))
print(c)

So the way I see it, zip(a, b) returns a zip object containing the following tuples: (1, 3), (2, 4). It is then converted to a list. I'm getting the following error:

TypeError: () missing 1 required positional argument: 'y'

So my guess is that the lambda function is not taking the second number in each tuple.

Is there any way to do this?

Answer 1

Only one parameter for lambda like:

c = list(map(lambda x: sum(x), zip(a, b)))

But once we are using sum, we can map it directly like:

c = list(map(sum, zip(a, b)))

Test Code:

a = (1, 2)
b = (3, 4)
c = list(map(sum, zip(a, b)))
print(c)

Result:

[4, 6]

Answer 2

In Python2, you can use specific unpacking syntax in a lambda:

a = (1, 2)
b = (3, 4)
c = list(map(lambda (x, y): x+y, list(zip(a, b))))

However, in Python3, you will have to use sum:

c = list(map(lambda x_y: sum(x_y), list(zip(a, b))))