Travis E. Oliphant wrote: > Thomas J. Duck wrote: > >> Determining the minimum value of an array that contains NaN produces >> a surprising result: >> >> >>> x = numpy.array([0,1,2,numpy.nan,4,5,6]) >> >>> x.min() >> 4.0 >> >> I expected 0.0. Is this the intended behaviour or a bug? I am using >> numpy 1.1.1. >> >> > NAN's don't play well with comparisons because comparison with them is > undefined. See numpy.nanmin > This is not true! Each single comparison with a NaN has a well defined outcome. The difficulty is only that certain logical assumptions do not hold any more when NaNs are involved (e.g. [A<B] is not equivalent with [not(A>=B)]). Assuming an IEEE compliant processor and C compiler, it should be possible to code a NaN safe min routine without additional overhead.
_______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
