See below for Antonio Gonzalez solution (last year) that I have started using and happy with it
Neil M wrote: > Hello, > > Is it possible to plot two histograms on the same axis without having > the bars on top of each other. > > I'm trying to determine how similar a distribution of activity is > between a large data set and a small subset. > > I have 2 million records with a last activity date. I can plot both > the sample and the full population on a normalized histogram, and in > different colours but the later plot covers smaller values of the > earlier one. > > Thanks > Neil > -------- Original Message -------- Subject: Re: [Matplotlib-users] plotting overlapped histograms Date: Mon, 13 Nov 2006 19:02:03 +0100 From: Antonio Gonzalez <[EMAIL PROTECTED]> To: David E. Konerding <[EMAIL PROTECTED]> CC: Matplotlib-users@lists.sourceforge.net References: <[EMAIL PROTECTED]> To compare two histograms you can plot a bihistogram as suggested on http://www.itl.nist.gov/div898/handbook/eda/section3/bihistog.htm The little function I've written to do so is below. See if it helps. Antonio import scipy from pylab import figure def bihist(y1, y2, nbins=10, h=None): ''' Bihistogram. h is an axis handle. If not present, a new figure is created. ''' if h is None: h = figure().add_subplot(111) xmin = scipy.floor(scipy.minimum(y1.min(), y2.min())) xmax = scipy.ceil(scipy.maximum(y1.max(), y2.max())) bins = scipy.linspace(xmin, xmax, nbins) n1, bins1, patch1 = h.hist(y1, bins) n2, bins2, patch2 = h.hist(y2, bins) # set ymax: ymax = 0 for i in patch1: height = i.get_height() if height > ymax: ymax = height # invert second histogram and set ymin: ymin = 0 for i in patch2: height = i.get_height() height = -height i.set_height(height) if height < ymin: ymin = height h.set_ylim(ymin*1.1, ymax*1.1) h.figure.canvas.draw() _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
