[Numpy-discussion] Re: API: make numpy.lib._arraysetops.intersect1d work on multiple arrays #25688

Seems reasonable. I don't know if it is faster, but NumPy is all about vectorization. Surely speed needs to fit into equation somehow?

Another point to consider. Is function `in1d` able to achieve everything that `intersect1d` does? For 2 arrays of length 1600. def intersect1d_via_in1d(x, y): return np.unique(r1[np.in1d(x, y)]) %timeit np.intersect1d(r1, r2) # 927 µs ± 10.2 %timeit intersect1d_via_in1d(r1, r2) # 163 µs ± 1.73 Retrieving indices and other outputs that `intersect1d` provides also seems trivial. If it is faster and doesn’t consume more memory, then maybe it is more worthwhile re-using it in `intersect1d`? Regards, DG