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From: Jeff Klukas <klukas@wi...>  20100512 16:13:43
Attachments:
logyhist.png

When creating a histogram with histtype='stepfilled' and log=True, the fill always ends up getting cut off diagonally. It looks like it's connection one datapoint with 10^100 on the other side of the plot. So, also, it looks like it's always choosing 10^100 as an arbitrary lower limit, which is another problem. Is this a known bug? Does anybody have ideas for an intelligent way to handle stepfilled log histograms? A working example is below, with the output plot attached. Thanks, Jeff  Jeff Klukas, Research Assistant, Physics  University of Wisconsin  Madison  jeff.klukas@...  jeffyklukas@...  jeffklukas@...  http://www.hep.wisc.edu/~jklukas/  #!/usr/bin/env python import numpy as np import matplotlib.mlab as mlab import matplotlib.pyplot as plt mu, sigma = 100, 15 x = mu + sigma*np.random.randn(10000) # the histogram of the data n, bins, patches = plt.hist(x, 50, normed=1, facecolor='green', alpha=0.75, log=True, histtype='stepfilled') plt.xlabel('Smarts') plt.ylabel('Probability') plt.title(r'$\mathrm{Histogram\ of\ IQ:}\ \mu=100,\ \sigma=15$') plt.axis([40, 160, 0, 0.03]) plt.grid(True) plt.show()  
From: Jeff Klukas <klukas@wi...>  20100512 20:06:35

I've looked now through the source code for axes.hist, and I see where the problem is. If any value of any bin of the histogram is zero, then axes.fill fails, as zero is necessarily outside the y boundaries of the axes for log scale. Already, a default value of 1e100 is chosen for the first and last points given to axes.fill. If you also clean the histogram, replacing all zero yvalues with 1e100, then the fill succeeds. I see no downside to this treatment, since the default value has already been introduced. The user will still need to choose a reasonable lower limit for the yaxis. Any objections or concerns? Cheers, Jeff On Wed, May 12, 2010 at 11:13 AM, Jeff Klukas <klukas@...> wrote: > When creating a histogram with histtype='stepfilled' and log=True, the > fill always ends up getting cut off diagonally. It looks like it's > connection one datapoint with 10^100 on the other side of the plot. > So, also, it looks like it's always choosing 10^100 as an arbitrary > lower limit, which is another problem. > > Is this a known bug? Does anybody have ideas for an intelligent way > to handle stepfilled log histograms? > > A working example is below, with the output plot attached. > > Thanks, > Jeff > >  Jeff Klukas, Research Assistant, Physics >  University of Wisconsin  Madison >  jeff.klukas@...  jeffyklukas@...  jeffklukas@... >  http://www.hep.wisc.edu/~jklukas/ > >  > #!/usr/bin/env python > import numpy as np > import matplotlib.mlab as mlab > import matplotlib.pyplot as plt > > mu, sigma = 100, 15 > x = mu + sigma*np.random.randn(10000) > > # the histogram of the data > n, bins, patches = plt.hist(x, 50, normed=1, facecolor='green', alpha=0.75, > log=True, histtype='stepfilled') > > plt.xlabel('Smarts') > plt.ylabel('Probability') > plt.title(r'$\mathrm{Histogram\ of\ IQ:}\ \mu=100,\ \sigma=15$') > plt.axis([40, 160, 0, 0.03]) > plt.grid(True) > > plt.show() >  > 
From: Jeff Klukas <klukas@wi...>  20100513 15:12:08

I was using matplotlib 0.99.1.1. I just set up an Ubuntu system in VirtualBox so I could run the current svn trunk, and all is well. It looks like the fix has already been implemented. On Wed, May 12, 2010 at 3:06 PM, Jeff Klukas <klukas@...> wrote: > I've looked now through the source code for axes.hist, and I see where > the problem is. If any value of any bin of the histogram is zero, > then axes.fill fails, as zero is necessarily outside the y boundaries > of the axes for log scale. > > Already, a default value of 1e100 is chosen for the first and last > points given to axes.fill. If you also clean the histogram, replacing > all zero yvalues with 1e100, then the fill succeeds. I see no > downside to this treatment, since the default value has already been > introduced. > > The user will still need to choose a reasonable lower limit for the yaxis. > > Any objections or concerns? > > Cheers, > Jeff > > On Wed, May 12, 2010 at 11:13 AM, Jeff Klukas <klukas@...> wrote: >> When creating a histogram with histtype='stepfilled' and log=True, the >> fill always ends up getting cut off diagonally. It looks like it's >> connection one datapoint with 10^100 on the other side of the plot. >> So, also, it looks like it's always choosing 10^100 as an arbitrary >> lower limit, which is another problem. >> >> Is this a known bug? Does anybody have ideas for an intelligent way >> to handle stepfilled log histograms? >> >> A working example is below, with the output plot attached. >> >> Thanks, >> Jeff >> >>  Jeff Klukas, Research Assistant, Physics >>  University of Wisconsin  Madison >>  jeff.klukas@...  jeffyklukas@...  jeffklukas@... >>  http://www.hep.wisc.edu/~jklukas/ >> >>  >> #!/usr/bin/env python >> import numpy as np >> import matplotlib.mlab as mlab >> import matplotlib.pyplot as plt >> >> mu, sigma = 100, 15 >> x = mu + sigma*np.random.randn(10000) >> >> # the histogram of the data >> n, bins, patches = plt.hist(x, 50, normed=1, facecolor='green', alpha=0.75, >> log=True, histtype='stepfilled') >> >> plt.xlabel('Smarts') >> plt.ylabel('Probability') >> plt.title(r'$\mathrm{Histogram\ of\ IQ:}\ \mu=100,\ \sigma=15$') >> plt.axis([40, 160, 0, 0.03]) >> plt.grid(True) >> >> plt.show() >>  >> > 