Re: Pick up coordinates along different contours.
- To: mathgroup at smc.vnet.net
- Subject: [mg43390] Re: Pick up coordinates along different contours.
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Tue, 16 Sep 2003 04:35:40 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <bihpbq$b5t$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
suppose you need the lines from fun[]
fun[x_, y_] := Cos[Sqrt[x^2 + y^2]]
gr = Graphics[
ContourPlot[fun[x, y], {x, -2Pi, 2Pi}, {y, -2Pi, 2Pi},
Contours -> {-1/2, 1/2}, PlotPoints -> 30, DisplayFunction ->
Identity]]
one generates the contour graphics and convert it to an ordinary
Graphics[] with lines now you wish to select all lines, that include
points {x,y} with Abs[f[x,y]-level]< eps
level = 1/2;
dta = Select[Cases[gr, _Line, Infinity],
And @@ ( # < 0.05 & /@ (Abs[fun @@ # - level] & /@ First[#] ))
&];
Show[Graphics[dta, AspectRatio -> 1]];
eps (here 0.05) should be not too small because ContourPlot[] is not
very accurate ..
Regards
Jens
Jun Lin wrote:
>
> I plot a couple of 2D contours by using ContourPlot. Now, I want to
> pick up the coordinate of each point along each contour for next step
> calculation purposes. I appreciate with your any suggestion of how to
> get the coordinates of each point along a specific contour (suppose
> two contours have been created).
>
> Jun