In matplotlib 1.5.3 (installed with pip on Ubuntu, both over python 2.7.6 and 3.4.3) there seems to be an inconsistency of automatic axes limits in polar plots when a scatter plot is used. I first saw the issuein this question on Stack Overflow, and it boils down to this short example comparingplot andscatter:

import matplotlib.pyplot as pltr = range(8)ph = [-0.2]*len(r)fig,(ax1,ax2) = plt.subplots(ncols=2,subplot_kw={'polar':True})ax1.plot(ph,r,'o')ax2.scatter(ph,r)ax1.set_title('plot')ax2.set_title('scatter')plt.show()

The left axes plots the points usingplot, and the axes limits are nicely adjusted. The right axes usesscatter, and most of the points are missing as the limits are not updated correctly to fit the data. Note that the default radial (y) top limit would be 1, so there is some rescaling going on, but it is incorrect. Settingax2.set_ylim(0,max(r)) of course reproduces the scaling of the left axes.