Re: [Matplotlib-users] [ANN] basemap matplotlib toolkit 0.1.1

[Ted D. <ted...@jp...>]

Thanks for all the advice!  We're going to start working on this ground 
track plotting package in the March-April time frame so I'm going to save 
off these notes for the implementor.  We'll let you know if we need any 
more help then.

Thanks,
Ted

At 01:25 PM 2/11/2005, John Hunter wrote:
> >>>>> "Ted" == Ted Drain <ted...@jp...> writes:
>     Ted> For example, if I have a data set that looks like this:
>
>     Ted> [155,2] [165,4] [175,6] [-175,8] [-165,10] [-155,12]
>
>     Ted> I really need this data to be drawn as two separate lines:
>     Ted> [155,2] [165,4] [175,6] [180,7]
>
>     Ted> and [-180,7] [-175,8] [-165,10] [-155,12]
>
>     Ted> Ideally these two segments should be treated as a single line
>     Ted> wherever applicable (legend, style, etc).
>
>Got it -- what comes immediately to mind is for you to create a new
>class derived from Line2D, that contains your 2...N lines as private
>attrs,  defines __getattr__ to return the attr of line[0], and calls
>the Line2D parent setattr on each of your contained line instances.
>You can then add this line to the Axes with add_line.
>
>You would have to be a little clever with the get_xdata and get_ydata
>attrs, which are used for autoscaling.  If this looks like a good way
>to go, I can help you with it if you want  - it could be tricky to get
>just right.
>
>The other possibility would be to setup an observer pattern on the
>line0 properties, such that any changes would be fired off to the
>observers.  This is an area where it would be nice to have enthought
>traits built-in, since all trains support observers.  As you may have
>noticed on the dev list, this is an area of active discussion.
>
>
>     Ted> I'd probably label this as a "mostly acceptable work-around"
>     Ted> since it requires generating two data arrays.  In my case,
>     Ted> the data is expensive to compute so we'd probably have to
>     Ted> generate a second array by selectively copying points from
>     Ted> the first array which is kind of annoying.  I was hoping for
>     Ted> a keyword that said how often to generate the markers for an
>     Ted> existing line (with the default as one of course).  Probably
>     Ted> not a huge deal though.
>
>If this becomes a performance problem for you, another idea would be
>to use a marker mask.  Eg add an additional property to the line class
>which are the indices at which to write markers.
>
>Currently the line class is hairy in CVS, mainly because it is
>supporting the old and newstyle backend drawing interfaces.  The
>newstyle interface has only two renderer methods that it calls
>(draw_lines and draw_markers).  It would be fairly easy to subclass
>Line2D to support a marker mask, possibly passing it on as a kwarg to
>the renderer.draw_markers method.  One could do it in Numeric a the
>python level; if you are looking for optimal performance, it would be
>barely more than a no-op at the backend level.
>
>
>JDH
>
>
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Ted Drain     Jet Propulsion Laboratory   ted...@jp...