gdistance (version 1.6.4)

accCost: Accumulated Cost Surface

Description

Calculates the accumulated cost surface from one or more origins.

Usage

accCost(x, fromCoords)

Value

a RasterLayer object

Arguments

x

object of class TransitionLayer

fromCoords

origin point locations (SpatialPoints, matrix or numeric class)

Author

Jacob van Etten

Details

If more than one coordinate is supplied in fromCoords, the function calculates the minimum least-cost distance from any origin point.

The function uses Dijkstra's algorithm (as implemented in the igraph package).

References

E.W. Dijkstra. 1959. A note on two problems in connexion with graphs. Numerische Mathematik 1, 269 - 271.

See Also

geoCorrection, costDistance

Examples

library("raster")
# example equivalent to that in the documentation on r.cost in GRASS
r <- raster(nrows=6, ncols=7,
            xmn=0, xmx=7,
            ymn=0, ymx=6,
            crs="+proj=utm +units=m")

r[] <- c(2, 2, 1, 1, 5, 5, 5,
         2, 2, 8, 8, 5, 2, 1,
         7, 1, 1, 8, 2, 2, 2,
         8, 7, 8, 8, 8, 8, 5,
         8, 8, 1, 1, 5, 3, 9,
         8, 1, 1, 2, 5, 3, 9)

# 1/mean: reciprocal to get permeability
tr <- transition(r, function(x) 1/mean(x), 8)
tr <- geoCorrection(tr)

c1 <- c(5.5,1.5)
c2 <- c(1.5,5.5)

A <- accCost(tr, c1)
plot(A)
text(A)