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pythonnumpy
MichaelJanz
MichaelJanz

Reputation: 1815

Numpy: Find the maximum length of arrays inside another array

I have a numpy array as the following:

import numpy as np
arr = np.array([np.array([1]),np.array([1,2]),np.array([1,2,3]),np.array([1,3,4,2,4,2])])

I want a nice numpy function, which gives me the maximum length of the arrays inside my arr array. So I need a numpy function, which return for this example 6.

This is possible with iteration, but I am looking for a nicer way, perhaps even without map()

Any function inside tensorflow or keras would also be possible to use.

Upvotes: 1

Views: 1903

Answers (3)

Loochie
Loochie

Reputation: 2472

Another simple trick is to use max() function with key argument to return the array with maximum length.

len(max(arr, key = len))

Upvotes: 1

MichaelJanz
MichaelJanz

Reputation: 1815

Another way would be to use the keras.preprocessing.sequence.pad_sequences() function.

It pads the sequences to the lenght of the maximum, but in my opinion it creates a high memory usage and depending on the array it might take some time. However, this would be a way without looping:

len(keras.preprocessing.sequence.pad_sequences(arr)[0])

Upvotes: 0

ansev
ansev

Reputation: 30920

We could do:

max(map(len, arr))
#6

Upvotes: 3

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