Find function with numpy

Question

I have a numpy array and I want to find all the indexes that verifies a certain condition. Example, I want to plot the Heaviside function;

import numpy as np
x=np.linspace(-5,5,11)
k_neg=x.find(x<0)
k_pos=x.find(x>=0)
y=np.zeros(len(x))
y(k_neg)=-1
y(k_pos)=1

I don't find such a function (like it exists on Matlab).

Note : my actual problem IS NOT to plot Heavyside, of corse ;)

John · Accepted Answer · 2018-04-30 14:55:45Z

1

As said by Paul Panzer;

Sounds like you are looking for np.where

Which solved my problem.

answered Apr 30, 2018 at 14:55

John

3031 gold badge4 silver badges13 bronze badges

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

Comments

m33n · Accepted Answer · 2018-04-30 14:47:32Z

0

I would do it in one line with numpy:

import numpy as np
x = np.linspace(-5,5,11)
y = ((x>=0)*2)-1

answered Apr 30, 2018 at 14:47

m33n

1,76118 silver badges41 bronze badges

OP clearly states Heaviside is only a toy example. They want something more general.

I think this adapts to the given description but if you have a better idea please just post your solution!