R: Version of outer which operates only in a convex hull

outer.convhull {interp} | R Documentation

## Version of outer which operates only in a convex hull

### Description

This version of `outer` evaluates `FUN` only on that part of the grid cx times cy that is enclosed within the convex hull of the points (px,py).

This can be useful for spatial estimation if no extrapolation is wanted.

### Usage

    outer.convhull(cx,cy,px,py,FUN,duplicate="remove",...)

### Arguments

`cx` | x cordinates of grid
`cy` | y cordinates of grid
`px` | vector of x coordinates of points
`py` | vector of y coordinates of points
`FUN` | function to be evaluated over the grid
`duplicate` | indicates what to do with duplicate (px_i,py_i) points, default `"remove"`.
`...` | additional arguments for `FUN`

### Value

Matrix with values of `FUN` (`NA`s if outside the convex hull).

### Author(s)

Albrecht Gebhardt <albrecht.gebhardt@aau.at>, Roger Bivand <roger.bivand@nhh.no>

### See Also

`in.convex.hull`

### Examples

    x<-runif(20)
    y<-runif(20)
    z<-runif(20)
    z.lm<-lm(z~x+y)
    f.pred<-function(x,y)
      {predict(z.lm,data.frame(x=as.vector(x),y=as.vector(y)))}
    xg<-seq(0,1,0.05)
    yg<-seq(0,1,0.05)
    image(xg,yg,outer.convhull(xg,yg,x,y,f.pred))
    points(x,y)

[Package interp version 1.0-33 Index]