raster (version 1.7-6)

pointDistance: Distance between points

Description

Calculate the geographic distance between two points on a sphere (latlong=TRUE) or on a plane (latlong=FALSE).

Usage

pointDistance(point1, point2, longlat=FALSE, ...)

Arguments

point1

x and y coordinate of first (set of) point(s), either as c(x, y) or as matrix(ncol=2) in degrees for great-circle distance, in meters (or similar) for Euclidean

point2

x and y coordinate of second (set of) second point(s). Like point1. If point1 and point2 are both matrices they should have the same number of rows

longlat

Logical. If TRUE, coordinates should be in degrees; else they should represent 'euclidean' space (e.g. units of meters)

...

Additional arguments. Can be used to set the radius, r, of the world (modeled as a sphere), when longlat=TRUE Default is r=6378137

Value

• A single value or a vector of values giving the distance in meters (longlat=TRUE) or map-units (for instance, meters in the case of UTM)

See Also

distanceFromPoints, distance, gridDistance

Examples

a <- cbind(c(1,5,55,31),c(3,7,20,22))
b <- cbind(c(4,2,8,65),c(50,-90,20,32))   

pointDistance(c(0, 0), c(1, 1), longlat=FALSE)
pointDistance(c(0, 0), c(1, 1), longlat=TRUE)
pointDistance(c(0, 0), a, longlat=TRUE)
pointDistance(a, b, longlat=TRUE)
   
#Make a distance matrix (dist object)
dst <- matrix(nrow=4,ncol=4)
for (i in 1:4){dst[,i] <- pointDistance(a[i,],a, longlat=TRUE)}
dst <- as.dist(dst)
   
#The same as above, but avoiding the loop
dst <- pointDistance(a[rep(1:4,times=4),],a[rep(1:4,each=4),], longlat=TRUE)
dst <- as.dist(matrix(dst,ncol=4))