Michael Droettboom wrote: > jason-s...@creativetrax.com wrote: >> I'm trying to deal nicely with the clipping that happens when, for >> example, a line has data that is inside its clipping box, but the >> linewidth forces part of the line to be drawn outside of the clipping >> box. This is visible on the spine placement demo at >> http://matplotlib.sourceforge.net/examples/pylab_examples/spine_placement_demo.html, >> >> for example (the clipping at the top and bottom of most of the sine >> waves). This has been brought up here (or on the -devel list) >> before, and it was suggested to just set the clipping off, but that >> won't work in my case because sometimes I want to use that clipping >> box to limit the data shown. >> >> The best solution I can think of is to expand the clipping box by >> padding it with the line width. For something like a scatter plot, I >> would also be okay with expanding the clipping box by padding by the >> max radius of a circle in the circle collection. However, I can't >> quite figure out how to do this with the transform framework. If I >> just pad the clip box using the padded() method, it seems to make it >> a static Bbox instead of a TransformedBbox, and my line disappears. >> Can someone help? >> > Yeah -- that sounds rather painful. We don't currently have a way to > dynamically grow a bbox like this and have it updated on > zooming/panning etc. I think what ultimately needs to happen is that > clipping is made aware of the spine placement (which is a relatively > new feature) and automatically deal with these small adjustments of > the clipping box. I'm thinking of the Axes clip_box becoming > something dynamically calculated based on the placement of the > spines. But I think it will be much harder to do it from the > outside. Of course, it's hard to say if this is the right thing to do > in the general case -- we'll always end up clipping some marker or > another if the limits of the axes are anything but the limits of the > actual data. Hmm... I'll have to think on this some more.
Thanks for thinking about this. My use-case (matplotlib in Sage) is just static pictures (at least until maybe the html5 canvas backend comes around!) >> Another option I thought of was separating out masking the data from >> clipping the graphics. I suppose if I could get the data for the >> line and mask it to be within the clipbox, but then just set clipping >> off, I would still have the benefit of clipping things that were way >> outside of my bounding box, but letting things like an extra bit of >> linewidth through. However, this requires doing things like >> computing intersections of the line and the bounding box so that I >> can insert an extra point for the "end" of the line at the bounding >> box. This gets harder when the line is a spline or something like that. >> > Do you care about panning and zooming, or are you just creating static > plots? If static, then you can just pass in a masked array as the > data and all of these things should be handled automatically (with the > exception of splines). Something like: > > In [1]: X = np.arange(0, np.pi * 2.0, 0.001) > > In [3]: Y = np.sin(X) > > In [4]: X = ma.masked_where(X > np.pi * 1.5, X) > > In [5]: Y = ma.masked_where((Y < -0.5) | (Y > 0.5), Y) > > In [6]: plot(X, Y) I thought about this, but often, in Sage, we adjust the axes limits *after* we have plotted the data. So I would have to find all lines and circles and whatever else in the graph, get the data out, and mask it. Would I then have to redraw it too? also, if it is a long, straight line defined by two points that goes out of the clip box, I probably want to insert a point at the intersection so it looks like the line is just being clipped. Between these two problems, it seemed like the better solution was just padding the clip box by the line width. I'm still trying to understand the transformation system. In linear algebra, to make the box grow by just a bit, I would translate the clip box to the origin, scale by a certain amount (probably based on fig.dpi_scale_something_or_other), then translate the clip box back. Would this work? On the other hand, what if I hooked into the on_draw method and padded the clip box there, similar to the FAQ example of making really long text labels fit? Thanks, Jason ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
