Dividing elements of array Python

Question

Hello I'm a beginner programmer and I know there must be a simple way to do this but for some reason can't find the answer. I have two arrays and just want to divide each element by the elements in the other array. for example

a= np.array([2,4,6,8,10,12])
b=np.array([2,1,2,1,2,1])
so that the result is (1,4,3,8,5,12)....

I tried doing this over a for loop :

for i in range(a):
    c = a[i]/b[i]

but it doesnt work and gives the error "TypeError: only integer arrays with one element can be converted to an index"

Try a / b without the for loop, numpy does sensible things with mathematical operations on the whole array. — AChampion
– AChampion, Commented May 10, 2017 at 16:15
a/b will work as others have pointed out. The other problem is that you have range(a) where you should use range(len(a)). — VBB
– VBB, Commented May 10, 2017 at 16:39
@VBB yes I found out that that was my real problem, thank you! — Katey
– Katey, Commented May 10, 2017 at 18:45

wpercy · Accepted Answer · 2017-05-10 16:31:00Z

6

You can just divide the arrays themselves (a/b)

In [1]: import numpy as np

In [2]: a = np.array([2,4,6,8,10,12])

In [3]: b = np.array([2,1,2,1,2,1])

In [4]: a/b
Out[4]: array([ 1,  4,  3,  8,  5, 12])

This happens because numpy overloads the __div__ method of the ndarray to divide the elements of the arrays and output the resulting array (the implementation is mostly in C code so it'd be difficult to link you to exactly where this happens)

edited May 10, 2017 at 16:31

answered May 10, 2017 at 16:17

wpercy

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1 Comment

jsbueno Over a year ago

Just please, don't forget to clarify the direct division is possible due to the nature of Numpy operator overloading.

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