Re: Contour Lines
- To: mathgroup at smc.vnet.net
- Subject: [mg83610] Re: Contour Lines
- From: Thomas E Burton <tburton at brahea.com>
- Date: Sat, 24 Nov 2007 04:17:59 -0500 (EST)
In the spirit of the notion that a fishing pole is better in the long
run than a fish, let me share a recipe to solve this:
1. Look into plot1, note the expression GraphicsComplex.
2. GraphicsComplex is new to v6, so look it up in help.
3. Follow your nose, leading to something like the following:
pointList = Cases[plot1, GraphicsComplex[points_,
data_] :> Cases[data, Line[pts : {__Integer}] :> points
[[pts]], Infinity]
][[1, 1]]
or
pointList = Cases[
Cases[plot1, gc_GraphicsComplex:> Normal[gc]],
Line[points_List] :> points, Infinity][[1]]
I use Cases so I don't have to remember where things are. You can
certainly shorten these expressions.
Tom
> How do you extract the coordinates of points making up a Contour
> Line as a List?
>
> This has been dealt with before in the archive (see e.g., ) but the
> code there seems no longer to work. ...
>
> Convert the ContourGraphics to Graphics and then extract the first
> part and you will see how Mathematica represents the contours.
>
> contour = First@Graphics@plot1 (output omitted) ...