Contour levels
- To: mathgroup at smc.vnet.net
- Subject: [mg83766] Contour levels
- From: sigmundv at gmail.com
- Date: Fri, 30 Nov 2007 05:15:26 -0500 (EST)
A few days ago a question was posted on how to extract the coordinates
defining each of the contours returned by ContourPlot[]. Then I would
like to ask if there is any way to also get the level they belong to?
Let me illustrate the question by an example:
If I plot the contours (or level curves) of the scalar function f(x,y)
= x^2 + y^2 by using
cplot = ContourPlot[x^2+y^2,{x,-1,1},{y,-1,1}]
in Mathematica 6.0, I get a few circles. The points defining these
circles are extracted as follows:
Cases[First[cplot] // Normal, Line[pts_] -> pts, Infinity];
This returns a few lists, each containing a selection of points on a
circle. Then my question is, if there is any way I can get the level
to which each of these lists belong. That is, can I ask Mathematica
which list of points belongs to f(x,y) = 0.4, for example, or, which
level does a given list of points belong to?
Kind regards,
Sigmund Vestergaard