Yannick Copin wrote: > Hi, > > I would like to plot lots of error ellipses on my plot. I thought I > could use an EllipseCollection to do so, but I didn't manage to get the > ellipse sizes, expressed in data units, right (see test script attached). > > When using a plain list of Ellipse's, everything looks fine: > > ells = [ P.matplotlib.patches.Ellipse(xy=xyi, > width=wi, height=hi, > angle=ai, > edgecolor='b', > facecolor='b', > alpha=0.3) > for xyi,wi,hi,ai in zip(xy,w,h,a)] > for ell in ells: > ax.add_artist(ell) > > But when using EllipseCollection (as explained in > http://matplotlib.sourceforge.net/examples/pylab_examples/ellipse_collection.html), > > > > coll = P.matplotlib.collections.EllipseCollection(widths=w, > heights=h, > angles=a, > units='x', > offsets=xy, > transOffset=ax.transData, > edgecolor='r', > facecolor='r', > alpha=0.3) > ax.add_collection(coll) > > the size of the ellipses (expressed in data units) appears incorrect, > and depends furthermore of the aspect ratio of the figure (try pan/zoom > or resize the interactive window).
Maybe I am misunderstanding, but the EllipseCollection in the example is panning and zooming as I expect. The shapes and orientations are staying the same while the scale expands and contracts with the x-axis. The problem is that the option you are looking for does not exist yet. I am not sure yet whether what you need is identical to an option I added to quiver (from which I partially derived EllipseCollection). I suspect it is. Do you want width to scale with x and height to scale with y? And the angle to scale such that a 45-degree angle always corresponds to equal increments in x and in y, all in data units? > > I naively thought the two approaches should give the same result... Did > I miss something in the way to use EllipseCollections? EllipseCollection is derived more from quiver than from Ellipse. Eric ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
