A few thoughts: 1) don't use arange() for flaoting point numbers, use linspace().
2) histogram1d is a floating point function, and you shouldn't expect exact results for floating point -- in particular, values exactly at the bin boundaries are likely to be "uncertain" -- not quite the right word, but you get the idea. 3) if you expect have a lot of certain specific values, say, integers, or zeros -- then you don't want your bin boundaries to be exactly at the value -- they should be between the expected values. 4) remember that histogramming is inherently sensitive to bin position anyway -- if these small bin-boundary differences matter, than you may not be using teh best approach. -HTH, -Chris > >>> data > array([ 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , > 0. , 0.05, -0.05]) > >>> bins_list = numpy.array([-0.1, -0.05, 0.0, 0.05, 0.1]) > >>> (counts, edges) = numpy.histogram(data, bins=bins_list) > >>> counts > array([ 0, 1, 10, 1]) > >>> edges > array([-0.1 , -0.05, 0. , 0.05, 0.1 ]) > > > > but this does not (generating the bin values via bumpy.arange): > > >>> bins_arange = numpy.arange(-0.1, 0.101, 0.05) > >>> data > array([ 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , > 0. , 0.05, -0.05]) > >>> bins_arange > array([-0.1 , -0.05, 0. , 0.05, 0.1 ]) > >>> (counts, edges) = numpy.histogram(data, bins=bins_arange) > >>> counts > array([ 0, 1, 11, 0]) > > I'm assuming this is due to slight rounding in the calculation of > bins_arange, > as compared to the manually entered values in bins_list. > > What is the recommended way of getting the first set of results, without > having to manually enter all the values in the "bins" argument? > > The following also gives me unexpected results: > > >>> data > array([ 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , 0. , > 0. , 0.05, -0.05]) > counts, edges) = numpy.histogram(data, range=(-0.1, 0.1), bins=4) > >>> counts > array([ 0, 1, 11, 0]) > > > > Thank you for any advice, > > Catherine > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception chris.bar...@noaa.gov
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