Re: Extracting points from a contour plot

*To*: mathgroup at smc.vnet.net*Subject*: [mg90415] Re: Extracting points from a contour plot*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Tue, 8 Jul 2008 07:49:32 -0400 (EDT)*Organization*: Uni Leipzig*References*: <g4v34e$ihi$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, cntr = ContourPlot[Sin[Pi^2*x*y], {x, 0, 1}, {y, 0, 1}, Contours -> {0}, ContourShading -> False]; pnts = cntr[[1, 1]]; pidx = Union[Flatten[Cases[cntr, _Line, Infinity] /. Line -> List]]; ll = pnts[[#]] & /@ pidx; and Graphics[Point[ll]] will show you, that you have found the right points. And the accuracy of the generated points will to low in the most cases. Regards Jens ajfriend at gmail.com wrote: > I'm not a Mathematica expert, so hopefully this isn't too stupid of a > question: > > I'm using ContourPlot to plot the curve of zeros of a function of two > variables within a range of vales (0 < x < 1, 0 < y < 1). Now, what I > really want is the list of points that it generates. I've tried > playing with Solve and NSolve, but these are either not working or are > taking too long. What is the easiest way of getting at the list of > points that ContourPlot has generated? Do I have to do something like > InputForm[%] and then cut and paste the list that I want, or is there > some easier way of doing it? > > Or, maybe there is a way of getting the points that I want without > using ContourPlot that I haven't come across yet, or maybe I'm just > not using Solve correctly. > > Any help would be great. > > Thanks, > AJ >