How to use NumPy to sort a multidimensional array from highest to lowest value

Question

Not sure I'm finding my exact use case in the NumPy documentation, so hoping for help.

I have this array:

X = np.array([
            [Larry, 90%],
            [Beth, 100%],
            [Arnold, 90%],
])

And I'm trying to sort these horizontal pairs by the second index (i.e., the percentage) from highest to lowest value so that the result is:

            ([
            [Beth, 100%],
            [Arnold, 90%],
            [Larry, 90%],
])

I tried using argsort, but the expression below didn't work:

X = X[-X[:, 0].argsort()]

First, to refer to the second index/column, 'X[:, 1]' should be used. Second, to sort, you may want to convert a string to a float number. — Ricardo
– Ricardo, Commented Jul 26, 2022 at 0:49

Ricardo · Accepted Answer · 2022-07-26 00:32:38Z

1

import numpy as np
X = np.array([['Larry', '90%'], ['Beth', '100%'], ['Arnold', '90%']])
X[np.array([-float(num.strip('%'))/100 for num in X[:, 1]]).argsort()]

answered Jul 26, 2022 at 0:32

Ricardo

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jkr Over a year ago

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