Searching an element's index in a numpy array

Question

I have a "distances" numpy array. I want to find the index of an element. I used numpy.where condition but it is not returning the index. Instead, it is just returning the type of the element with an empty array, like so:

(array([], dtype=int64),)

What should I do to get the index of the element? Please help. Thanks.

This is my code:

distances = distances_query_training(features_train, features_test[2])

print min(distances)

print type(distances)

pos = np.where(distances == 0.03471681)

print pos

And the following is the output:

0.0347168063061
(array([], dtype=int64),)

HYRY · Accepted Answer · 2016-02-13 04:11:18Z

2

Don't use equal to float values, use isclose():

import numpy as np

np.random.seed(1)
a = np.random.rand(1000)

np.where(np.isclose(a, 0.3, atol=1e-4))

answered Feb 13, 2016 at 4:11

HYRY

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Comments

filippo · Accepted Answer · 2016-02-13 14:03:29Z

1

Do you need all the close elements or just the best matching one? I usually do something like this to get the closest index for a value

def nearest_arg(array, value):
    idx = (np.abs(array - value)).argmin()
    return idx

answered Feb 13, 2016 at 14:03

filippo

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1 Comment

Rahul Bohare Over a year ago

I needed the best matching one. And your function works really well. Thanks for the help. :-)

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