make.tri {secr}

R Documentation

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", ...)

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

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.

Note

Several methods are provided for manipulating detector arrays - see traps.

See Also

make.grid, detector

Examples

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 )

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