project2set {spatstat.geom}

Find Nearest Point in a Region

Description

For each data point in a point pattern X, find the nearest location in a given spatial region W.

Usage

  project2set(X, W, ...)

Arguments

X

Point pattern (object of class "ppp").

W

Window (object of class "owin") or something acceptable to as.owin.

...

Arguments passed to as.mask controlling the pixel resolution.

Details

The window W is first discretised as a binary mask using as.mask.

For each data point X[i] in the point pattern X, the algorithm finds the nearest pixel in W.

The result is a point pattern Y containing these nearest points, that is, Y[i] is the nearest point in W to the point X[i].

Value

A point pattern (object of class "ppp") with the same number of points as X in the window W.

Author(s)

Adrian Baddeley [e-mail]

Rolf Turner [e-mail]

and Ege Rubak [e-mail]

See Also

project2segment, nncross

Examples

  He <- heather$fine[owin(c(2.8, 7.4), c(4.0, 7.8))]
  plot(He, main="project2set")
  W <- erosion(complement.owin(He), 0.2)
if(require(spatstat.random)) {
  X <- runifpoint(4, W)
} else {
  X <- ppp(c(6.1, 4.3, 5.7, 4.7), c(5.0, 6.6, 7.5, 4.9), window=W)
}
  points(X, col="red")
  Y <- project2set(X, He)
  points(Y, col="green")
  arrows(X$x, X$y, Y$x, Y$y, angle=15, length=0.2)