exclude.too.far {mgcv} | R Documentation |

## Exclude prediction grid points too far from data

### Description

Takes two arrays defining the nodes of a grid over a 2D covariate space and two arrays
defining the location of data in that space, and returns a logical vector with elements `TRUE`

if
the corresponding node is too far from data and `FALSE`

otherwise. Basically a service routine for
`vis.gam`

and `plot.gam`

.

### Usage

exclude.too.far(g1,g2,d1,d2,dist)

### Arguments

`g1` |
co-ordinates of grid relative to first axis. |

`g2` |
co-ordinates of grid relative to second axis. |

`d1` |
co-ordinates of data relative to first axis. |

`d2` |
co-ordinates of data relative to second axis. |

`dist` |
how far away counts as too far. Grid and data are first scaled so that the grid lies exactly
in the unit square, and `dist` is a distance within this unit square. |

### Details

Linear scalings of the axes are first determined so that the grid defined by the nodes in
`g1`

and `g2`

lies exactly in the unit square (i.e. on [0,1] by [0,1]). These scalings are
applied to `g1`

, `g2`

, `d1`

and `d2`

. The minimum Euclidean
distance from each node to a datum is then determined and if it is greater than `dist`

the
corresponding entry in the returned array is set to `TRUE`

(otherwise to `FALSE`

). The
distance calculations are performed in compiled code for speed without storage overheads.

### Value

A logical array with `TRUE`

indicating a node in the grid defined by `g1`

, `g2`

that
is `too far' from any datum.

### Author(s)

Simon N. Wood simon.wood@r-project.org

### References

http://www.stats.gla.ac.uk/~simon/

### See Also

`vis.gam`

### Examples

library(mgcv)
x<-rnorm(100);y<-rnorm(100) # some "data"
n<-40 # generate a grid....
mx<-seq(min(x),max(x),length=n)
my<-seq(min(y),max(y),length=n)
gx<-rep(mx,n);gy<-rep(my,rep(n,n))
tf<-exclude.too.far(gx,gy,x,y,0.1)
plot(gx[!tf],gy[!tf],pch=".");points(x,y,col=2)

[Package

*mgcv* version 1.3-12

Index]