make.tri: Build Detector Array on Triangular or Hexagonal Grid

Description

Construct an array of detectors on a triangular grid and optionally select a hexagonal subset of detectors.

Usage

make.tri (nx = 10, ny = 12, spacing = 20, detector = "multi",
    originxy = c(0,0))
clip.hex (traps, side = 20, centre = c(50, 60*cos(pi/6)),
    fuzz = 1e-3, ID = "num", ...)

Value

An object of class traps comprising a data frame of x- and y-coordinates, the detector type ("single", "multi", or "proximity" etc.), and possibly other attributes.

Arguments

nx: number of columns of detectors
ny: number of rows of detectors
spacing: distance between detectors (x and y directions)
detector: character value for detector type - "single", "multi" etc.
originxy: vector origin for x-y coordinates
traps: traps object
side: length of hexagon side
centre: x-y coordinates of hexagon centre
fuzz: floating point fuzz value
ID: character string to control row names
...: other parameters passed to subset.traps (not used)

Details

make.tri generates coordinates for nx.ny traps at separations spacing. The bottom-left (southwest) corner is at originxy. Identifiers are numeric. See make.grid for further explanation.

clip.hex clips a grid of detectors, retaining only those within a bounding hexagon. Detectors are re-labelled according to ID as follows:

ID	Effect
NULL	no change
num	numeric sequence
alpha	letter for`shell'; number within shell

Examples

Run this code


tri.grid <- make.tri(spacing = 10)
plot(tri.grid, border = 5)

hex <- clip.hex(tri.grid, side = 30, ID = "alpha")
plot (hex, add = TRUE, detpar = list(pch = 16, cex = 1.4),
    label = TRUE, offset = 2.5 )