Re: [Matplotlib-users] Novice question: Am I using pyplot.rgrids correctly?

[Andre' Walker-L. <wal...@gm...>]

> I am a matplotlib.pyplot novice, but I have looked through various FAQs to no avail.
> 
> I am plotting a polar graph with some negative values of r.  Everything goes well until I try to use rgrids().  Am I doing something wrong?
> 
> I attach some demo scripts and their outputs.
> 
> version1.py uses rgrid() but only has positive values of r.  Everything works the way I expect it to (see version1.png).
> 
> version2.py has negative values of r and the same call to rgrid() and misbehaves (see version2.png).
> 
> version3.py is the same as version2.py, but without the call to rgrids() (but with negative values of r).  Again everything is as expected.
> 
> What am I doing wrong in version2.py?

and only because it (sadly) took me a few minutes to figure out (even though it seemed so obvious), to create the plot of your version 3, with only positively defined values for "r", you can do 

t = numpy.linspace(0,2*numpy.pi,61)
r = t
t2 = numpy.linspace(-numpy.pi,numpy.pi,61)
r2 = numpy.pi - t2

plt.polar(t,r)
plt.polar(t2,r2)



andre