np.unique needs an option to retain the original order

This would integrate the work-around solutions of a number of stackoverflow questions, such as:

http://stackoverflow.com/questions/15637336/numpy-unique-with-order-preserved

['b','b','b','a','a','c','c']

numpy.unique gives ['a','b','c']

How can I get the original order preserved ['b','a','c']

The issue with these workarounds is that you can get the unique list unsorted but it is much more complicated to get a matching list with counts (from the return_counts boolian).

Having an integrated boolian (i.e. is_sorted=True) for sorting of results would clear up this issue and increase the utility of the function.

[h-vetinari]

I would need this functionality as well…

Regarding the ambiguity discussion: FWIW, pandas has implemented a “stable” (does not change order) unique, with the unambiguous choice of using either the 'first' or the 'last' occurrence of an element for determining the position in the unique output.

[dprada]

+1