Eric Firing wrote: > Ian, > > I have applied your patch and modified contourf_demo slightly to illustrate > interior masking. Thanks very much for the beautiful work! These contour > bugs that you fixed were major mpl problems--general embarrassments, and > specific impediments to my own applications, since the data sets I work with > often have masked interior regions. (And, I also use line contours on top > of filled contours, so the saddle-point decision fix helps as well.)
I'm glad my contribution passes the quality control checks! > It occurs to me that there might be a nice refinement: when following a > masked boundary, how hard would it be to cross the single-cell gap > diagonally instead of proceeding step-wise along the boundary? In the case > of the circular masked region that I added to the contourf_demo, this would > simply smooth out the boundary of that region. > > Eric I think it would be fairly easy to do half a solution to this, but difficult to do it properly. It would be easy to change the edge_walker function to miss out a grid point when, for example, moving clockwise around a masked region from an i-edge to a j-edge. But what should happen in the situations when a contour level intersects one of those two edges: either (a) do nothing, or (b) still do the diagonal cut-off. The do nothing option (a) is easy (!) but means that there will be a mixture of diagonal cut-offs and stepwise changes, which won't look particularly elegant, whereas (b) will mean some pretty serious rewriting as the contouring code will have to deal with these diagonal edges for both contour lines and filled contours, and there will have to be some slightly arbitrary interpolation from the grid z-values to these diagonal edges. So the answer to your question is "difficult but doable". My preference is to leave it as it is, as the current blocky solution is what I expect to see. But I am happy to take a look at it if you/others think it is a good idea. On the subject of contouring masked grids, I sometimes want to specify which grid squares are masked rather than which grid points, i.e. for a grid of nx by ny points I want to specify a mask of (nx-1) by (ny-1) squares. I've discovered that cntr.c uses such a square mask, creating it from the incoming point mask. It would therefore be easy to add support for such a grid by changing the python front end to pass it in. Is this a good idea and would this be useful to others, or am I being overly simplistic? Ian P.S. Eric, I see that you work with Kelvin Richards - he was my PhD supervisor many years ago. Small world! ------------------------------------------------------------------------------ Throughout its 18-year history, RSA Conference consistently attracts the world's best and brightest in the field, creating opportunities for Conference attendees to learn about information security's most important issues through interactions with peers, luminaries and emerging and established companies. http://p.sf.net/sfu/rsaconf-dev2dev _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
