[Numpy-discussion] histogram using decending range -- what do the results mean?
Robert Kern
robert.kern@gmail....
Fri Oct 5 17:04:47 CDT 2007
Mark.Miller wrote:
> Check how you're implementing the histogram function with respect to
> that range statement. It seems to make a difference, desirable or not.
>
> >>> import numpy
> >>> numpy.__version__
> '1.0.4.dev3982'
> >>> A = numpy.array([1, 2, 3, 4, 5, 6, 5, 4, 5, 4, 3, 2, 1])
> >>> (x, y) = numpy.histogram(A, range(0, 7))
> >>> x
> array([0, 2, 2, 2, 3, 3, 1])
> >>> y
> [0, 1, 2, 3, 4, 5, 6]
> >>>
> >>> (x, y) = numpy.histogram(A, range=(0, 7))
> >>> x
> array([0, 2, 2, 0, 2, 3, 0, 3, 1, 0])
> >>> y
> array([ 0. , 0.7, 1.4, 2.1, 2.8, 3.5, 4.2, 4.9, 5.6, 6.3])
Please check the signature of numpy.histogram(). The two aren't intended to be
the same. The range argument has nothing to do with the builtin range() function.
> >>>
> >>>
> >>> (x, y) = numpy.histogram(A, range(7,0))
> >>> x
> array([], dtype=int32)
> >>> y
> []
> >>>
>
> Note that in the last case, the histogram function isn't returning
> anything for a descending range.
>
> Also notice that you're overwriting a python function with the way
> you're assigning things....
No, he's not. "range" is a keyword argument to histogram(). He's using it correctly.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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