XY <- expand.grid(x=1:11, y=1:11) XY$z <- XY$x+XY$y contour(interp(XY$x, XY$y, XY$z))
hope this helps. spencer graves
Thomas W Blackwell wrote:
Dear L Z -
Before using contour() one needs to interpolate the z values to all points in a rectangular grid. 2D interpolation is not trivial. The package KernSmooth (case-sensitive) will do this for a density estimate but not, apparently, when z values are given. Perhaps packages splines or mclust will do this, although I haven't checked. More likely, the functions surf.ls(), surf.gls() from package spatial.
Other users who are familiar with maps and geographic information systems (GIS) packages for R may have much better ideas for you than I know about. I've never had occasion to use any of this.
- tom blackwell - u michigan medical school - ann arbor -
On Fri, 19 Dec 2003, L Z wrote:
Question: I have matrix (n x3) that represents discrete data. Each row of matrix is 3-D point (x,y,z). I would like to get contour map (z value) at two dimension (x,y). How can I use related contour function to do this job? I am not sure if I clarify this question. For example, we can get point (x,y) at 2 dimension according to first two columns of matrix. Then I want to connect same value z=(x,y). Thanks! zhang
The data file looks like this: X y z 4 0.33 0.99 4 0.5 1.2 5 0.66 1.2 5 0.7 1.5 6 2 1.2 ?
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