in python, compare two array in element and change the lower value to zero

Question

now we have two arrays

a = [[1.,2.,3.,4.,5.,6.,7.,8.,9.],[9.,8.,7.,6.,5.,4.,3.,2.,1.]]

b = [[2.,2.,1.,2.,0.,2.,1.,2.,0.],[2.,2.,1.,2.,0.,2.,1.,2.,0.]]

Is there any fast way to achieve the following function: compare these two arrays by element, and change the array a[] in the following rule:

if a[i,j] > b[i,j]: 

    a[i,j] = a[i,j] 

else   

a[i,j] = 0

I know that a loop can do it, but I am wondering if there is any other faster way to do it.

aless80 · Accepted Answer · 2017-07-26 02:51:41Z

3

import numpy as np
a = np.array([[1.,2.,3.,4.,5.,6.,7.,8.,9.],[9.,8.,7.,6.,5.,4.,3.,2.,1.]])
b = np.array([[2.,2.,1.,2.,0.,2.,1.,2.,0.],[2.,2.,1.,2.,0.,2.,1.,2.,0.]])

gr = np.greater(a,b)
a = np.multiply(a,gr)

The gr and a arrays become:

[[False False  True  True  True  True  True  True  True]
 [ True  True  True  True  True  True  True False  True]]

array([[ 0.,  0.,  3.,  4.,  5.,  6.,  7.,  8.,  9.],
       [ 9.,  8.,  7.,  6.,  5.,  4.,  3.,  0.,  1.]])

answered Jul 26, 2017 at 2:51

aless80

3,4405 gold badges38 silver badges55 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

in python, compare two array in element and change the lower value to zero

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related