[Numpy-discussion] Faulty behavior of numpy.histogram?

Danny Handoko danny.handoko@asml....
Wed Aug 12 02:12:09 CDT 2009

Dear all,

We try to use numpy.histogram with combination of matplotlib.  We are using numpy 1.3.0, but a somewhat older matplotlib version of 0.91.2.
Matplotlib's  axes.hist() function calls the numpy.histogram, passing through the 'normed' parameter.  However, this version of matplotlib uses '0' as the default value of 'normed' (I see it fixed in higher version).  What I found strange is that if the 'normed' parameter of numpy.histogram is set with other object than 'True' or 'False', the output becomes None, but no exceptions are raised.  As a result, the matplotlib code that does something like this:

>>> n, bins = numpy.histogram([1,2,3], 10, range = None, normed = 0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'NoneType' object is not iterable
results in the above exception.

Secondly, this matplotlib version also expects both outputs to be of the same length, which is no longer true with the new histogram semantics.  This can be easily reverted using the parameter 'new = False' in numpy.histogram, but this parameter is not available for the caller of axes.hist() function in matplotlib.  Is there any way to tell numpy to use the old semantics?

Upgrading to the newer matplotlib is a rather longer term solution, and we hope to be able to find some workaround/short-term solution

Thank you,


Danny Handoko

System Architecture and Generics

Room 7G2.003 -- ph: x2968

email: danny.handoko@asml.com

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