CODEWITHSUNDEEP
pythonnumpy
Chaos
Chaos

Reputation: 209

Find the index corresponding to the max value of a numpy array

I have a numpy.array of data called f, I know the max value in it is f_max=max(f) but I would like to know the index in the array corresponding to the maximum value.

I tried:

count = 0
while (f[count]!=fmax)
    conto ++

but I receive an error: 

SyntaxError: invalid syntax

Could anyone help me?

Upvotes: 0

Views: 5297

Answers (2)

acrider
acrider

Reputation: 406

If you're already using numpy, you can do this with argmax().

import numpy as np
a = np.array([1, 5, 2, 6, 3])

index = a.argmax()

Upvotes: 4

Sukrit Kalra
Sukrit Kalra

Reputation: 34531

The easiest way would be to find the max and then, look for its index.

>>> a = [1, 5, 2, 3, 4]
>>> val = max(a)
>>> a.index(val)
1

You could also use enumerate to get a list of indices and the values corresponding to them and choose the max among them.

>>> list(enumerate(a))
[(0, 1), (1, 5), (2, 2), (3, 3), (4, 4)]
>>> index, _ = max(enumerate(a), key = lambda x: x[1])
>>> index
1

Upvotes: 1

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