[Numpy-discussion] Conditional update of recarray field
Wed Nov 28 06:47:18 CST 2012
I try to update values in a single field of numpy record array based on
a condition defined in another array. I found that that the result
depends on the order in which I apply the boolean indices/field names.
cond = np.zeros(5, dtype=np.bool)
cond[2:] = True
X = np.rec.fromarrays([np.arange(5)], names='a')
X[cond]['a'] = -1
returns: [(0,) (1,) (2,) (3,) (4,)] (the values were not updated)
X['a'][cond] = -1
returns: [(0,) (1,) (-1,) (-1,) (-1,)] (it worked this time).
I find this behaviour very confusing. Is it expected? Would it be
possible to emit a warning message in the case of "faulty" assignments?
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