shortestPath: Shortest path

In gdistance: Distances and Routes on Geographical Grids

Description

Calculates the shortest path from an origin to a goal.

Usage

shortestPath(x, origin, goal, ...)

Arguments

x	TransitionLayer object
origin	SpatialPoints, vector or matrix with coordinates, at the moment only the first cell is taken into account
goal	SpatialPoints, vector or matrix with coordinates
...	Additional argument: output

Details

As an additional argument output, the desired output object can be specified: either “TransitionLayer” (default), “TransitionStack” or “SpatialLines”.

If there is more than one path either (1) transition values in the TransitionLayer get values of 1 / number of paths or (2) the SpatialLines object will contain more than one line.

Value

Transition object.

Author(s)

Jacob van Etten [e-mail].

See Also

costDistance, accCost

Examples

#example equivalent to that in the documentation on r.cost/r.drain 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)

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

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

#make a SpatialLines object for visualization
sPath1 <- shortestPath(T, c1, c2, output="SpatialLines")
plot(r)
lines(sPath1)

#make a TransitionLayer for further calculations
sPath2 <- shortestPath(T, c1, c2)
plot(raster(sPath2))

Example output

Loading required package: raster
Loading required package: sp
Loading required package: igraph

Attaching package: 'igraph'

The following object is masked from 'package:raster':

    union

The following objects are masked from 'package:stats':

    decompose, spectrum

The following object is masked from 'package:base':

    union

Loading required package: Matrix

Attaching package: 'gdistance'

The following object is masked from 'package:igraph':

    normalize

NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files
NOTE: rgdal::checkCRSArgs: no proj_defs.dat in PROJ.4 shared files

gdistance documentation built on May 2, 2019, 5:46 p.m.