[Numpy-discussion] histogram using decending range -- what do the results mean?
Mark.Miller
mpmusu@cc.usu....
Fri Oct 5 17:14:47 CDT 2007
My bad...I also note that I forgot to decrement the descending list in
my example. Ignore....
Robert Kern wrote:
> 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.
>
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