Could non-monotonicity be detected as part of the interp process? Perhaps a sign switch in the deltas?
I have been bitten by this problem too. Cheers! Ben Root On Jun 4, 2013 9:08 PM, "Eric Firing" <efir...@hawaii.edu> wrote: > > On 2013/06/04 2:05 PM, Charles R Harris wrote: > > > > > > On Tue, Jun 4, 2013 at 12:07 PM, Slavin, Jonathan > > <jsla...@cfa.harvard.edu <mailto:jsla...@cfa.harvard.edu>> wrote: > > > > Hi, > > > > I would like to suggest that the behavior of numpy.interp be changed > > regarding treatment of situations in which the x-coordinates are not > > monotonically increasing. Specifically, it seems to me that interp > > should work correctly when the x-coordinate is decreasing > > monotonically. Clearly it cannot work if the x-coordinate is not > > monotonic, but in that case it should raise an exception. Currently > > if x is not increasing it simply silently fails, providing incorrect > > values. This fix could be as simple as a monotonicity test and > > inversion if necessary (plus a raise statement for non-monotonic cases). > > > > > > Seems reasonable, although it might add a bit of execution time. > > The monotonicity test should be an option if it is available at all; > when interpolating a small number of points from a large pair of arrays, > the single sweep through the whole array could dominate the execution > time. Checking for increasing versus decreasing, in contrast, can be > done fast, so handling the decreasing case transparently is reasonable. > > Eric > > > > > Chuck > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion
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