spread: Functions to calculate a gaussian resistant kernel for a...

In ethanplunkett/gridprocess: Package for processing raster data

Functions to calculate a gaussian resistant kernel for a focal cell on a cost surface.

Description

This function returns a matrix where the value of each cell is a gaussian function of the least cost path between the cell and a focal cell.

Usage

spread(x, ...)  # generic
## S3 method for class 'matrix'
spread(x, row, col, sd, cellsize=1, sd.threshold=3, ...)
## S3 method for class 'grid'
spread(x, row, col, sd,  sd.threshold = 3, ...)

Arguments

x	the cost or resistance surface. Higher values indicate greater cost of movement. All values must be greater than one.
row, col	the focal row and column of the kernel.
sd	the standard deviation of the kernel (in map units).
cellsize	The dimension of each cell (in map units).
sd.threshold	This is the threshold in standard deviations beyond which the height will not be calculated and will be assumed to be zero. To calculate the threshold in map units multiple this value by sd.
...	Arguments to be passed to other methods.

Value

An object of the same class as x containing the spread values.

Author(s)

Ethan Plunkett, Brad Compton, and Eduard Ene

References

Compton, B.W., K. McGarigal, S.A. Cushman, and L.R. Gamble. 2007. A resistant-kernel model of connectivity for amphibians that breed in vernal pools. Conservation Biology 21:788-799. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1111/j.1523-1739.2007.00674.x")}

McGarigal, K., B.W. Compton, E.B. Plunkett, W.V. DeLuca, J. Grand, E. Ene, and S.D. Jackson. 2018. A landscape index of ecological integrity to inform landscape conservation. Landscape Ecology 33:1029-1048. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1007/s10980-018-0653-9")}

See Also

rawspread calculates the cost distance and is called by this function. x2c and y2r will convert x and y coordinates to row and column indicies.

Examples

	rs <- matrix(1, nrow=20, ncol=20)
	rk <- spread(rs, 10, 10, 3)	
	image(rk)
	rs[,12:13] <- 2
	rk2 <- spread(rs, 10, 10, 3)
	image(rk2)

ethanplunkett/gridprocess documentation built on Feb. 1, 2024, 2:24 a.m.