From: Manuel Metz <mmetz@as...>  20080519 20:07:13

Hi, I had one or two more looks at the hist() function. There are a few things I wondered about: (I) Isn't it more intuitive to interpret the "width" keyword as "width relative to the real width of a bin" rather than as an absolute value ? Here is an example, why I think so: Say I want to create a histogram where the individual bars touch each other. First create some data In [3]: sigma * 38. In [4]: Y = sigma * numpy.random.randn(1000) In [5]: pylab.hist(Y) By default, this produces a histogram where there is some space between the bars. But how should I now (in advance) what the width will be? That depends on the retuned bins of the numpy.histogram routine, so the only direct solution would be In [6]: n, bins, patches = pylab.hist(Y) In [7]: pylab.clf() In [8]: n, bins, patches = pylab.hist(Y, width=bins[1]bins[0]) (II) If width < real_width_of_abin, why is the bar aligned to the left edge of the bin, not to its center? (That different from the align='center' behaviour). Try a width that is << real_width_of_abin . The result looks strange to me and is hard to interpret. (III) Now the real interesting thing !!! matlab has the ability to create a kind of combined histogram, if the input is not an 1d array, but a matrix. So, I played a little bit around and added such a feature to the matplotlib hist method. It isn't finished yet, but might be of interest ??? from pylab import * import numpy mu, sigma = 100, 15 x = mu + sigma*numpy.random.randn(1000,3) ret = hist(x, 10, normed=True) show() ... produces a figure as attached. Manuel 