Convert Data To Class ppp

Description

Tries to coerce any reasonable kind of data to a point pattern (an object of class "ppp") for use by the spatstat package).

Usage

  as.ppp(X)
  as.ppp(X, W)

Arguments

Details

This function tries to coerce the data X to a point pattern (an object of class "ppp"; see ppp.object for an overview). The optional argument W is a default window for the pattern; it is used only if a window is not specified in X.

The data X may be:

• an object of class "ppp"
• an object of class "spp" as used in the Venables and Ripley package spatial
• an object of class "quad" representing a quadrature scheme (see quad.object)
• a structure with entries x, y (vectors of equal length) and xl, xu, yl, yu (numbers giving the dimensions of a rectangular window)
• a two-column matrix
• a structure with entries x, y

In the last two cases, we need the second argument W which is converted to a window object by the function as.owin. In the first three cases, W will be ignored.

Point pattern datasets can also be created by the function ppp.

Value

An object of class "ppp" (see ppp.object) describing the point pattern and its window of observation.

Author(s)

Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner rolf@math.unb.ca http://www.math.unb.ca/~rolf

See Also

ppp, ppp.object, as.owin, owin.object

Examples

 library(spatstat)

 
 plot(c(0,1),c(0,1),type="n")
 xy <- locator(20) # click on 20 points in plot window
 pp <- as.ppp(xy, c(0,1,0,1))
 
 w <- owin(c(0,1),c(0,1))
 plot(w)                      # neater
 xy <- locator(20)            # click on 20 points in plot window
 pp <- as.ppp(xy, w)
  
 
 xy <- matrix(runif(40), ncol=2)
 pp <- as.ppp(xy, c(0,1,0,1))
 
 # Venables-Ripley format
 sp <- list(x=runif(10), y=runif(10), xl=0, xu=1, yl=0, yu=1)
 pp <- as.ppp(sp)   # converted to our format