On 2012/08/27 5:10 AM, Francesco Montesano wrote: > Dear matplotlibers, > > I encountered a bug (?) in fill_between when using logarithmic scales and > the last part of y and yerr arrays as set to zero: a diagonal stripe going > from > the rightmost non zero value to the first value is drawn. > It's visible in the right panel of the attached figure, while is not > present if the plot is linear (left panel). > If xaxis is log and yaxis is linear the plot is correctly drawn. > > I'm using mpl.__version__ = '1.1.1rc' under Kubuntu 12.04 with Python 2.7.3 > > The plot has been created with the script below. > > Is this a bug or am I missing something?
I don't think it is exactly a bug, but I don't know why the fill region is appearing as it does. The underlying problem is that fill_between is doing what it is told to do without knowing that it is going to be plotted on a log axis. A good workaround is to change your call to fill_between to look like this: positive = y - yerr > 0 ax2.fill_between( x,y-yerr,y+yerr, where=positive, color='b', alpha=0.4) Alternatively, you could use np.clip to put a floor under y - yerr and y + yerr. Eric > > Cheers > Francesco > > > ##### error_fill_between.py ###### > import matplotlib.pyplot as plt > import numpy as np > > #values to plot > x = np.linspace( 1, 10, num=100 ) > y = np.exp( -x**2 ) > y[50:] = 0 > yerr = y* np.random.rand(100) > > #figure > fig = plt.figure() > > ax1 = fig.add_subplot(121) #first axes: linear > ax1.errorbar( x,y,yerr, c='r' ) > ax1.fill_between( x,y-yerr,y+yerr, color='b', alpha=0.4 ) > > ax2 = fig.add_subplot(122) #second axes: logarithmic > ax2.errorbar( x,y,yerr, c='r' ) > ax2.fill_between( x,y-yerr,y+yerr, color='b', alpha=0.4 ) > ax2.set_xscale( "log" ) > ax2.set_yscale( "log" ) > > plt.show() > ###### end script ######### > > > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > > > > _______________________________________________ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
