spatstat (version 1.0-1)

plot.ppp: plot a Spatial Point Pattern

Description

Plot a two-dimensional spatial point pattern

Usage

plot.ppp(x, main, ..., chars, use.marks=TRUE, add=FALSE)

Arguments

x

The spatial point pattern to be plotted. An object of class "ppp", or data which can be converted into this format by as.ppp().

main

text to be displayed as a title above the plot.

...

extra arguments passed to the generic plot function.

chars

the plotting characters which should be used to represent the points with different marks. See below.

use.marks

logical flag; if TRUE, plot points using a different plotting symbol for each mark; if FALSE, only the locations of the points will be plotted, using points().

add

logical flag; if TRUE, just the points are plotted, over the existing plot. A new plot is not created, and the window is not plotted.

Value

• NULL, or a vector giving the correspondence between mark values and plotting characters.

Details

This is the plot method for the class "ppp" (see ppp.object for details of this class). It invokes plot.owin to display the observation window x$window. Then the locations of the points are plotted using points(). If the points do not have marks (i.e. x$marks is absent) or if use.marks = FALSE, then the locations of the points will be plotted using a single plot character. This character can be changed by the extra argument pch; see the examples. If the points have marks, then each mark value will be represented by a different plot character. This action can be overridden by setting use.marks = FALSE. For marked point patterns the default is to represent the $i$th unique mark value by points(..., pch=i). If the vector chars is supplied, it should have the same length as sort(unique(x$marks)), and then the $i$th smallest mark will be plotted using points(..., pch=chars[i]).

See Also

ppp.object, plot, points, plot.owin

Examples

library(spatstat)

   data(cells)
   plot(cells)

   # multitype 
   data(lansing)
   plot(lansing)

   # marked by a real number
   data(longleaf)
   plot(longleaf)

   # just plot the points
   plot(longleaf, use.marks=F)
   plot(unmark(longleaf)) # equivalent

   # use selected plot characters
   lma <- sort(unique(longleaf$marks))
   adult <- ifelse(lma >= 30, "o", "+")
   plot(longleaf, chars = adult)