I have 2 1D numpy arrays of the same dimension, a and b, and I want to sort
the arrays using the values in b. This can be achieved with lists as outlined
in this previous post or by using numpy’s argsort.
First we make some example data
import numpy as np
a = np.array(range(99,109))
b = np.array(np.arange(500,1000,50))
np.random.shuffle(b)So our data looks like:
>>> print a
[ 99 100 101 102 103 104 105 106 107 108]
>>> print b
[ 700 550 650 800 750 500 950 600 850 900]We can then use argsort on b to get the indexes of b if it was sorted:
indexes = b.argsort()
>>> print indexes
[5 1 7 2 0 4 3 8 9 6]And then apply these indexes to our original data to reorder it:
a = a[indexes]
b = b[indexes]Which yields:
>>> print a
[104 100 106 101 99 103 102 107 108 105]
>>> print b
[ 500 550 600 650 700 750 800 850 900 950]