Ranking of numpy array with possible duplicates

Question

I have a numpy array of floats/ints and want to map its elements into their ranks.

If an array doesn\'t have duplicates the problem can be solved by the following co

Answer 1

After upgrading to a latest version of scipy as suggested @WarrenWeckesser in the comments, scipy.stats.rankdata seems to be faster than both scipy.stats.mstats.rankdata and np.searchsorted being the fastet way to do it on larger arrays.

In [1]: import numpy as np

In [2]: from scipy.stats import rankdata as rd
   ...: from scipy.stats.mstats import rankdata as rd2
   ...: 

In [3]: array = np.arange(0.1, 1000000.1)

In [4]: %timeit np.searchsorted(np.sort(array), array)
1 loops, best of 3: 385 ms per loop

In [5]: %timeit rd(array)
10 loops, best of 3: 109 ms per loop

In [6]: %timeit rd2(array)
1 loops, best of 3: 205 ms per loop