Create a Line Segment Pattern
Creates an object of class "psp" representing
a line segment pattern in the two-dimensional plane.
psp(x0,y0, x1, y1, window, marks=NULL,
check=spatstat.options("checksegments"))x0 |
Vector of x coordinates of first endpoint of each segment |
y0 |
Vector of y coordinates of first endpoint of each segment |
x1 |
Vector of x coordinates of second endpoint of each segment |
y1 |
Vector of y coordinates of second endpoint of each segment |
window |
window of observation,
an object of class |
marks |
(optional) vector or data frame of mark values |
check |
Logical value indicating whether to check that the line segments lie inside the window. |
In the spatstat library, a spatial pattern of line segments is
described by an object of class "psp". This function
creates such objects.
The vectors x0, y0, x1 and y1 must be
numeric vectors of equal length. They are interpreted as the cartesian
coordinates of the endpoints of the line segments.
A line segment pattern is assumed to have been observed within a specific
region of the plane called the observation window.
An object of class "psp" representing a point pattern
contains information specifying the observation window.
This window must always be specified when creating a point pattern dataset;
there is intentionally no default action of “guessing” the window
dimensions from the data points alone.
The optional argument marks is given if the line segment pattern
is marked, i.e. if each line segment carries additional information.
For example, line segments which are classified into two or more different
types, or colours, may be regarded as having a mark which identifies
which colour they are.
The object marks must be a vector of the same length
as x0, or a data frame with number of rows equal to the
length of x0. The interpretation is that marks[i]
or marks[i,] is the mark attached to the ith line
segment. If the marks are real numbers then marks should
be a numeric vector, while if the marks takes only a finite number
of possible values (e.g. colours or types) then marks
should be a factor.
See psp.object for a description of the class
"psp".
Users would normally invoke psp to create a line segment pattern,
and the function as.psp to convert data in another
format into a line segment pattern.
An object of class "psp"
describing a line segment pattern in the two-dimensional plane
(see psp.object).
Adrian Baddeley Adrian.Baddeley@curtin.edu.au and Rolf Turner r.turner@auckland.ac.nz.
Function for extracting information from a segment pattern:
marks.psp,
summary.psp,
midpoints.psp,
lengths_psp
angles.psp,
endpoints.psp
Convert line segments to infinite lines: extrapolate.psp.
X <- psp(runif(10), runif(10), runif(10), runif(10), window=owin()) m <- data.frame(A=1:10, B=letters[1:10]) X <- psp(runif(10), runif(10), runif(10), runif(10), window=owin(), marks=m)
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