[Numpy-discussion] np.unique with structured arrays

[Nicolas P. Rougier]

Hello,

I've found a strange behavior or I'm missing something obvious (or np.unique is not supposed to work with structured arrays).

I'm trying to extract unique values from a simple structured array but it does not seem to work as expected.
Here is a minimal script showing the problem:

import numpy as np

V = np.zeros(4, dtype=[("v", np.float32, 3)])
V["v"] = [ [0.5,    0.0,   1.0],
           [0.5, -1.e-16,  1.0], # [0.5, +1.e-16,  1.0] works
           [0.5,    0.0,  -1.0],
           [0.5, -1.e-16, -1.0]] # [0.5, +1.e-16, -1.0]] works
V_ = np.zeros_like(V)
V_["v"][:,0] = V["v"][:,0].round(decimals=3)
V_["v"][:,1] = V["v"][:,1].round(decimals=3)
V_["v"][:,2] = V["v"][:,2].round(decimals=3)

print np.unique(V_)
[([0.5, 0.0, 1.0],) ([0.5, 0.0, -1.0],) ([0.5, -0.0, 1.0],) ([0.5, -0.0, -1.0],)]


While I would have expected:

[([0.5, 0.0, 1.0],) ([0.5, 0.0, -1.0],)]


Can anyone confirm ?


Nicolas
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