Convert Data To Class owin
Converts data specifying an observation window
in any of several formats, into an object of class "owin".
as.owin(W, ..., fatal=TRUE) ## Default S3 method: as.owin(W, ..., fatal=TRUE) ## S3 method for class 'owin' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'ppp' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'psp' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'quad' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'quadratcount' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'tess' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'im' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'layered' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'data.frame' as.owin(W, ..., step, fatal=TRUE) ## S3 method for class 'distfun' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'nnfun' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'funxy' as.owin(W, ..., fatal=TRUE) ## S3 method for class 'boxx' as.owin(W, ..., fatal=TRUE)
W |
Data specifying an observation window, in any of several formats described under Details below. |
fatal |
Logical value determining what to do if the data cannot be converted to an observation window. See Details. |
... |
Ignored. |
step |
Optional. A single number, or numeric vector of length 2, giving the grid step lengths in the x and y directions. |
The class "owin" is a way of specifying the observation window
for a point pattern. See owin.object for an overview.
The generic function as.owin converts data in any of several formats
into an object of class "owin" for use by the spatstat
package. The function as.owin is generic, with methods
for different classes of objects, and a default method.
The argument W may be
an object of class "owin"
a structure with entries xrange, yrange specifying the
x and y dimensions of a rectangle
a structure with entries named xmin, xmax, ymin,
ymax (in any order)
specifying the x and y dimensions of a rectangle.
This will accept objects of class bbox in the sf package.
a numeric vector of length 4
(interpreted as (xmin, xmax, ymin, ymax) in that order)
specifying the x and y dimensions of a rectangle
a structure with entries named xl, xu, yl, yu
(in any order)
specifying the x and y dimensions of a rectangle
as (xmin, xmax) = (xl, xu) and
(ymin, ymax) = (yl, yu). This will accept objects of
class spp used in the Venables and Ripley spatial
package.
an object of class "ppp" representing a point pattern.
In this case, the object's window structure will be
extracted.
an object of class "psp" representing a line segment pattern.
In this case, the object's window structure will be
extracted.
an object of class "tess" representing a tessellation.
In this case, the object's window structure will be
extracted.
an object of class "quad" representing a quadrature scheme.
In this case, the window of the data component will be
extracted.
an object of class "im" representing a pixel image.
In this case, a window of type "mask" will be returned,
with the same pixel raster coordinates as the image.
An image pixel value of NA, signifying that the pixel
lies outside the window, is transformed into the logical value
FALSE, which is the corresponding convention for window masks.
A data.frame with exactly three columns. Each row of the
data frame corresponds to one pixel. Each row contains the
x and y coordinates of a pixel, and a logical value
indicating whether the pixel lies inside the window.
A data.frame with exactly two columns. Each row of the
data frame contains the x and y coordinates of a pixel
that lies inside the window.
an object of class "distfun", "nnfun"
or "funxy" representing a function of spatial location,
defined on a spatial domain. The spatial domain of the function will be
extracted.
an object of class "layered" representing a
list of spatial objects. See layered.
In this case, as.owin will be applied to each
of the objects in the list, and the union of these windows
will be returned.
an object of class "SpatialPolygon",
"SpatialPolygons" or "SpatialPolygonsDataFrame".
To handle these data types,
the package maptools must be loaded,
because it provides the methods for as.owin for these classes.
For full details, see vignette('shapefiles').
If the argument W is not in one of these formats
and cannot be converted to a window, then an error will
be generated (if fatal=TRUE) or a value of NULL
will be returned (if fatal=FALSE).
When W is a data frame, the argument step
can be used to specify the pixel grid spacing; otherwise, the spacing
will be guessed from the data.
An object of class "owin" (see owin.object)
specifying an observation window.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk.
Additional methods for as.owin are provided
in the maptools package:
as.owin.SpatialPolygon,
as.owin.SpatialPolygons,
as.owin.SpatialPolygonsDataFrame.
w <- as.owin(c(0,1,0,1))
w <- as.owin(list(xrange=c(0,5),yrange=c(0,10)))
# point pattern
data(demopat)
w <- as.owin(demopat)
# image
Z <- as.im(function(x,y) { x + 3}, unit.square())
w <- as.owin(Z)
# Venables & Ripley 'spatial' package
spatialpath <- system.file(package="spatial")
if(nchar(spatialpath) > 0) {
require(spatial)
towns <- ppinit("towns.dat")
w <- as.owin(towns)
detach(package:spatial)
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