generate.density: Defining an Animal Population Density

In dill/wisp: Wildlife Simulation Package (wisp)

Description

The function creates a two dimensional density matrix which defines the distribution of an animal population inside a region.

Usage

        generate.density(reg, nint.x = 100, nint.y = 100, southwest = 1, southeast = 1, northwest = 1)

Arguments

reg	a region onto which the density is mapped
nint.x	number of x-intervals in the density matrix.
nint.y	number of y-intervals in the density matrix.
southwest	density value at the south-western corner of the region.
southeast	density value at the south-eastern corner of the region.
northwest	density value at the north-western corner of the region.

Details

This function places a ‘nint.x’ by ‘nint.y’ grid over the survey region; using linear interpolation and the three density values at ‘southwest’, ‘southeast’ and ‘northwest’, it calculates relative densities at other grid points in the region. The resulting density matrix defines a relative density plane. Note that the density surface is relative; it is proportional to the density of animal groups but absolute density depends on the number of groups in the region (which is set using setpars.population). Higher resolution grids are created by increasing ‘nint.x’ and/or ‘nint.y’. Stips or blocks of constant density can be added using the function set.stripe; bell-shaped density "bumps" or "dips" can be added using add.hotspot.

Value

An object of class 'density.population´ which has the following elements:

n.interval.x	number of x-intervals
n.interval.y	number of y-intervals
matrix	the density matrix.

See Also

generate.region summary.density.population plot.density.population add.hotspot set.stripe

Examples

reg <- generate.region(x.length = 50, y.width = 80)
dens <- generate.density(reg)
     
# image plot:
plot(dens, method = "image")

# 3-D wireframe plot:
plot(dens, eye.horiz=330, eye.vert=35)

# generate another density matrix with ascending density
reg <- generate.region(x.length = 50, y.width = 80)
dens <- generate.density(reg, nint.x = 50, nint.y = 40, southwest = 1, southeast = 10, northwest = 20)

# image plot:
plot(dens, method = "image")

# 3-D wireframe plot:
plot(dens, eye.horiz=330, eye.vert=35)

dill/wisp documentation built on May 15, 2019, 8:31 a.m.