| as.ppp {spatstat} | R Documentation |
Tries to coerce any reasonable kind of data to a point pattern
(an object of class "ppp")
for use by the spatstat package).
as.ppp(X, ..., fatal=TRUE) as.ppp(X, W, ..., fatal=TRUE)
X |
Data which will be converted into a point pattern |
W |
Data which define a window for the pattern
when X does not contain a window |
... |
Ignored. |
fatal |
Logical value. See Details. |
Converts the dataset X to a point pattern
(an object of class "ppp"; see ppp.object for
an overview).
This function is normally used to convert an existing point pattern
dataset, stored in another format, to the "ppp" format.
To create a new point pattern from raw data such as x,y
coordinates, it is normally easier to use the creator function
ppp.
The dataset X may be:
"ppp"
"spp" as defined in the
spatial library
"quad" representing a quadrature scheme
(see quad.object)
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.
The argument fatal indicates what to do when
W is missing and X contains no
information about the window. If fatal=TRUE, a fatal error
will be generated; if fatal=FALSE, the
value NULL is returned.
An spp object is the representation of a point pattern
in the spatial library. Our implementation recognises
the following formats:
x, y
xl, xu, yl, yu
x, y and area,
where area is a structure with entries
xl, xu, yl, yu
spatial versions 1 to 6 and version 7.1 respectively)
where x and y are vectors of equal length
giving the point coordinates, and xl, xu, yl,
yu are numbers giving the dimensions of a rectangular window.
The function as.ppp is generic, with methods for the
classes "ppp", "quad", "matrix"
and a default method.
Point pattern datasets can also be created by the function
ppp.
An object of class "ppp" (see ppp.object)
describing the point pattern and its window of observation.
The value NULL may also be returned; see Details.
If the format of spp objects
is changed in future versions of the spatial library,
then as.ppp may not be able to interpret them.
It currently handles all versions of spatial up to 7.1-4.
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
ppp,
ppp.object,
as.owin,
owin.object
## Not run:
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)
## End(Not run)
xy <- matrix(runif(40), ncol=2)
pp <- as.ppp(xy, c(0,1,0,1))
# Venables-Ripley format
require(spatial)
towns <- ppinit("towns.dat")
pp <- as.ppp(towns) # converted to our format
detach(package:spatial)