Python: How to sort an Array with with a combination of Strings and Integers

Question

I have the following array to represent the ranges for a column within a dataframe:

array(['72.5 - 80.0', '42.5 - 50.0', '57.5 - 65.0', '20.0 - 27.5',
   '35.0 - 42.5', '147.5 - 155.0', '192.5 - 200.0', '87.5 - 95.0',
   '95.0 - 102.5', '185.0 - 192.5', '117.5 - 125.0', '102.5 - 110.0',
   '162.5 - 170.0', '80.0 - 87.5', '170.0 - 177.5', '65.0 - 72.5',
   '140.0 - 147.5', '110.0 - 117.5', '132.5 - 140.0', '27.5 - 35.0',
   '50.0 - 57.5', '177.5 - 185.0', '155.0 - 162.5'], dtype=object)

I would like to sort it such that it looks something like this, basically in ascending order:

 array(['20.0 - 27.5', '27.5 - 35.0', '35.0 - 42.5', '42.5 - 50.0', ......

How should I go about it? Thank you!

Answer 1

You can use natsort :

from natsort import natsorted

np.array(natsorted(a), dtype=object)

Or sorted with a custom key :

np.array(sorted(a, key=lambda x: float(x.split('-')[0])), dtype=object)

Output:

array(['20.0 - 27.5', '27.5 - 35.0', '35.0 - 42.5', '42.5 - 50.0',
       '50.0 - 57.5', '57.5 - 65.0', '65.0 - 72.5', '72.5 - 80.0',
       '80.0 - 87.5', '87.5 - 95.0', '95.0 - 102.5', '102.5 - 110.0',
       '110.0 - 117.5', '117.5 - 125.0', '132.5 - 140.0', '140.0 - 147.5',
       '147.5 - 155.0', '155.0 - 162.5', '162.5 - 170.0', '170.0 - 177.5',
       '177.5 - 185.0', '185.0 - 192.5', '192.5 - 200.0'], dtype=object)