matplotlib-users Mailing List for matplotlib

Hi, I've been using matplotlib for about a week now and am exceedingly
confused by all the class hierarchies and stuff.
 
I'm trying to draw an arc and some other polygons and render them to either
GTK or postscript. I'm running Python 2.4 with Idle and XP
 
I can successfully do the following:
1. Using the matlab-ish commands, I can create a figure, polygons, circles,
and use add_patch() to add these shapes to the figure. 
2. I can direct it to GTK or PS with the matplotlib.use command. I can
print out the resulting PS file just fine, and the plot shows up on the
screen with GTK just fine.
 
The problem is I want to draw arcs. I don't see an Arc() command at the
same level as Polygon and Circle. The only place I see an arc is with the
renderer classes.
 
I tried extracting the current renderer from the figure and axis (via the
_cachedRenderer attribute), but those don't seem to be assigned until I do a
savefig() or a show(), but obviously I want the renderer before any
show()ing or savefig()ing.
 
So then I tried creating a RendererPS class directly (instead of RendererAgg
as in the User's Guide). It seems to want a pswriter argument. I looked
around and saw that pswriter is expected to be some type of cString.StringIO
or something, which seemed too low-level, and I figured I didn't want to
mess around any more. I just want to draw a stupid arc.
 
Also, if I have a GTK figure, and then do show(), it plots a nice figure on
the screen. If I then close it, type show() again, my python window freezes
up and I have to kill it with the process manager.
 
If anyone can shed some light on these problems I'd be much happier :-)
 
Thanks
Michael