CODEWITHSUNDEEP
pythonnumpyvectorization
Sai
Sai

Reputation: 43

Vectorizing Multi-Dimensional Operations in Python

I am wondering if vectorization can be applied to two vector inputs at once...

Consider the following simple function:

def f(x,y):
    return(x+y,x-y)

I want to give a function like this, two vectors x=arange(3) and y=arange(4,6). My instinct is to define a,b=f(x,y) but python tells me that these operators could not be broadcast with shapes (3) (2). Clearly this works if y (or x) were scalars.

Whats the way to do this? Is there one?

Upvotes: 2

Views: 243

Answers (1)

Nipun Batra
Nipun Batra

Reputation: 11367

This will work fine, if the dimensions of the vectors x and y are the same. You have the following code setup:

In [16]: x=arange(3)

In [17]: x
Out[17]: array([0, 1, 2])

In [18]: y=arange(4,6)

In [19]: y
Out[19]: array([4, 5])

Obviously, x+y are not defined. Since x has 3 entities (dimensions) and y has only 2.

Consider a slight modification:

In [21]: y=arange(4,7)

In [22]: x+y
Out[22]: array([4, 6, 8])

In [23]: x-y
Out[23]: array([-4, -4, -4])

Now, x+y and x-y work as expected.

Now your function will also work fine.

In [24]: def f(x,y):
....:     return (x+y,x-y)
....: 

In [25]: f(x,y)
Out[25]: (array([4, 6, 8]), array([-4, -4, -4]))

Upvotes: 1

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