Viewrendered will display an @pyplot node in the rendering pane. The node must contain correct matplotlib.pyplot code for this to work. The rendering pane displays your graph complete with the interactive controls.
ggplot is a very nice plotting package that uses pyplot behind the scenes. It turns out that VR can display @pyplot nodes that contain ggplot code as well. Ifgp is the name of your figure, just end the code with
gp.draw(return_ggplot=False, show=False)
There is no need to save the figure.
@pyplot doesn't work in VR3 as yet. That will be Coming Soon.