topoDistance (version 1.0.2)

topoDist: Topographic distances and paths

Description

Calculates shortest topographic distances and paths

Usage

topoDist(DEM, pts, directions = 8, paths = FALSE, zweight = 1)

Value

Matrix of topographic distances (if paths = FALSE), or a list containing a matrix of topographic distances and the topographic paths as an object of class SpatialLines (if paths = TRUE).

Arguments

DEM

A RasterLayer for digital elevation model (DEM) data.

pts

A SpatialPoints object or two-column matrix with xy coordinates for the geographic points from which to calculate pairwise distances and paths.

directions

numeric (default = 8). The number of directions for movement between cells, either 4 or 8.

paths

logical. Default is FALSE, in which case only topographic distances are calculated. If TRUE, topographic paths are also identified.

zweight

numeric (default = 1). The weight to be applied to the elevation (z) distances relative to the horizontal (xy) distances.

Details

If paths = FALSE, the function will return a matrix of pairwise topographic distances between the specified points. If paths = TRUE, the function will return a list with two items: (1) the matrix of pairwise topographic distances, and (2) a SpatialLines object containing the topographic paths.

Examples

xy <- matrix(ncol = 2, byrow = TRUE,
   c(-119.5566, 37.72474,
   -119.4718, 37.76078))
topoDist(Yosemite$DEM, xy, paths = TRUE)