# spokes

0th

Percentile

##### 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.

Keywords
spatial
##### Usage
spokes(x, y, nrad = 3, nper = 3, fctr = 1.5)
##### Arguments
x
Vector of $x$ coordinates of data points.
y
Vector of $y$ coordinates of data points.
Number of radii emanating from each data point.
nper
Number of dummy points per radius.
fctr
Scale factor. Length of largest spoke radius is fctr * M where M is the mean nearest neighbour distance for the data points.
##### Details

This function is useful in creating dummy points for quadrature schemes (see quadscheme).

Given the point pattern specified by the vectors x and 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 nrad radii emanating from (x[i],y[i]), with nper dummy points equally spaced along each radius.

The (equal) spacing of dummy points along each radius is controlled by the factor fctr. The distance from a data point to the furthest of its associated dummy points is fctr * M where M is the mean nearest neighbour distance for the data points.

##### Value

• A list with two components x and y, which are numeric vectors giving the coordinates of the dummy points.

• spokes
##### Examples
library(spatstat)
dat <- runifrect(10)
plot(dat)
dum <- spokes(dat$x, dat$y)
points(dum$x, dum$y, pch=".")