PERF: categorical rank #15498
Description
xref #15422 (comment)
easy enough after #15422 to rank the categories themselves rather than using expanded values; prob most relevant for object dtypes.
In [15]: s = Series(tm.makeCategoricalIndex(100000)) In [16]: res = Series(np.array(s.cat.rename_categories(Series(s.cat.categories).rank()))).rank() In [17]: res2 = s.rank() In [18]: res.equals(res2) Out[18]: True In [19]: %timeit Series(np.array(s.cat.rename_categories(Series(s.cat.categories).rank()))).rank() 100 loops, best of 3: 4.39 ms per loop In [20]: %timeit s.rank() 10 loops, best of 3: 132 ms per loop