July 23, 2010
10:37 a.m.
Fri, 23 Jul 2010 10:29:47 -0400, Alan G Isaac wrote: [clip]
>>> np.subtract.reduce([]) 0.0
Getting a right identity for an empty array is surprising. Matching Python's behavior (raising a TypeError) seems desirable. (?)
I don't think matching Python's behavior is a sufficient argument for a change. As far as I see, it'd mostly cause unnecessary breakage, with no significant gain. Besides, it's rather common to define sum_{z in Z} z = 0 prod_{z in Z} z = 1 if Z is an empty set -- this can then be extended to other reduction operations. Note that changing reduce behavior would require us to special-case the above two operations. -- Pauli Virtanen