as.ppp | R Documentation |
Tries to coerce any reasonable kind of data to a spatial point pattern
(an object of class "ppp"
)
for use by the spatstat package).
as.ppp(X, ..., fatal=TRUE)
## S3 method for class 'ppp'
as.ppp(X, ..., fatal=TRUE)
## S3 method for class 'psp'
as.ppp(X, ..., fatal=TRUE)
## S3 method for class 'quad'
as.ppp(X, ..., fatal=TRUE)
## S3 method for class 'matrix'
as.ppp(X, W=NULL, ..., fatal=TRUE)
## S3 method for class 'data.frame'
as.ppp(X, W=NULL, ..., fatal=TRUE)
## Default S3 method:
as.ppp(X, W=NULL, ..., fatal=TRUE)
X |
Data which will be converted into a point pattern |
W |
Data which define a window for the pattern,
when |
... |
Ignored. |
fatal |
Logical value specifying what to do if the data cannot be converted. 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 function as.ppp
is generic, with methods for the
classes "ppp"
, "psp"
, "quad"
, "matrix"
,
"data.frame"
and a default method.
The dataset X
may be:
an object of class "ppp"
an object of class "psp"
a point pattern object created by the spatial library
an object of class "quad"
representing a quadrature scheme
(see quad.object
)
a matrix or data frame with at least two columns
a structure with entries x
, y
which are numeric vectors
of equal length
a numeric vector of length 2, interpreted as the coordinates of a single point.
In the last three cases, we need the second argument W
which is converted to a window object
by the function as.owin
.
In the first four cases, W
will be ignored.
If X
is a line segment pattern (an object of class psp
)
the point pattern returned consists of the endpoints of the segments.
If X
is marked then the point pattern returned will also be
marked, the mark associated with a point being the mark of the segment
of which that point was an endpoint.
If X
is a matrix or data frame, the first and second columns will
be interpreted as the x
and y
coordinates respectively.
Any additional columns will be interpreted as marks.
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.
In the spatial library, a point pattern is represented in either of the following formats:
(in spatial versions 1 to 6)
a structure with entries x
, y
xl
, xu
, yl
, yu
(in spatial version 7)
a structure with entries
x
, y
and area
,
where area
is a structure with entries
xl
, xu
, yl
, yu
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.
Point pattern datasets can also be created by the function
ppp
.
Methods for as.ppp
exist for some other classes of data;
they are listed by methods(as.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.
ppp
, ppp.object
, as.owin
,
owin.object
.
Methods for as.ppp
exist for some other classes of data;
they are listed by methods(as.ppp)
.
xy <- matrix(runif(40), ncol=2)
pp <- as.ppp(xy, c(0,1,0,1))
# Venables-Ripley format
# check for 'spatial' package
spatialpath <- system.file(package="spatial")
if(nchar(spatialpath) > 0) {
require(spatial)
towns <- ppinit("towns.dat")
pp <- as.ppp(towns) # converted to our format
detach(package:spatial)
}
xyzt <- matrix(runif(40), ncol=4)
Z <- as.ppp(xyzt, square(1))
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.