Spokes pattern of dummy points
Generates a pattern of dummy points in a window, given a data point pattern. The dummy points lie on the radii of circles emanating from each data point.
spokes(x, y, nrad = 3, nper = 3, fctr = 1.5)
- Vector of $x$ coordinates of data points.
- Vector of $y$ coordinates of data points.
- Number of radii emanating from each data point.
- Number of dummy points per radius.
- Scale factor.
Length of largest spoke radius is
fctr * Mwhere
Mis the mean nearest neighbour distance for the data points.
This function is useful in creating dummy points for quadrature
Given the point pattern specified by the vectors
y, the function
creates a pattern of
nrad * nper * length(x) dummy points.
Around each data point
(x[i],y[i]) there are
nrad * nper dummy points, lying on
nper dummy points
equally spaced along each radius.
The (equal) spacing of dummy points along each radius is
controlled by the factor
The distance from a data point to the furthest of its associated
dummy points is
fctr * M
M is the mean nearest neighbour distance
for the data points.
- A list with two components
y, which are numeric vectors giving the coordinates of the dummy points.
library(spatstat) dat <- runifrect(10) plot(dat) dum <- spokes(dat$x, dat$y) points(dum$x, dum$y, pch=".") Q <- quadscheme(dat, dum)