I have the following code/data:
import numpy as np
data = np.array([
[12, 1, 0.7, 0],
[13, 2, 0.5, 1],
[41, 3, 0.3, 0],
[20, 2, 0.8, 0],
[51, 2, 0.7, 0],
[32, 0, 0.9, 0],
[17, 4, 0.7, 1],
[54, 1, 0.6, 1],
[22, 1, 0.4, 1],
[74, 0, 0.5, 0],
[11, 4, 0.3, 1],
[13, 3, 0.8, 0],
[15, 4, 0.3, 0],
[65, 3, 0.2, 1],
])
I want to sort the 2d array: mainly by data[:, 1] in acending order (from lowest to highest) and secondly, data[:, 2] in decending order (highest to lowest) so I've come up with the following code:
data[:, 2] = -data[:, 2]
ind = np.lexsort((data[:, 2], data[:, 1]))
data[:, 2] = -data[:, 2]
data = data[ind]
print data
which have resulted:
[[ 32. 0. 0.9 0. ]
[ 74. 0. 0.5 0. ]
[ 12. 1. 0.7 0. ]
[ 54. 1. 0.6 1. ]
[ 22. 1. 0.4 1. ]
[ 20. 2. 0.8 0. ]
[ 51. 2. 0.7 0. ]
[ 13. 2. 0.5 1. ]
[ 13. 3. 0.8 0. ]
[ 41. 3. 0.3 0. ]
[ 65. 3. 0.2 1. ]
[ 17. 4. 0.7 1. ]
[ 11. 4. 0.3 1. ]
[ 15. 4. 0.3 0. ]]
Its correct. But I would like to know if theres a better way to do it. first if it is possible to do it in a shorter run-time. second, a more simple pytonic code.
to make it even shorter (and more pythonic) I can do this:
ind = np.lexsort((-data[:, 2], data[:, 1]))
data = data[ind]
Run-time still remains unanswered.
