pgirmess (version 1.3.8)

distSeg: Computes distances between the top coordinates of segments.

Description

Computes the distances between the top coordinates of segments.

Usage

distSeg(mydata,decdeg=FALSE)

Arguments

mydata

A matrix or data frame of 4 columns giving the coordinates of each segment tops x1, y1, x2, y2

decdeg

TRUE if point coordinates are longitude-latitude decimal degrees, in which case distances are measured in meters

Value

• A vector of distances

Details

If degdec is FALSE (default), distance computed is Euclidian. Units depends on the coordinate systems. If decdeg = TRUE, D = 1852 * 60 * (180/pi) * acos ( sin(la1) * sin(la2) + cos(la1) * cos(la2) * cos(abs(lg1 - lg2)). This method calculates the great circle distance, is based on spherical trigonometry, and assumes that:

• 1 minute of arc is 1 nautical mile
• 1 nautical mile is 1.852 km

See Also

distNode, distTot, distShp, distPolylines

Examples

x1<-rnorm(20)
y1<-rnorm(20)
x2<-rnorm(20)
y2<-rnorm(20)
mydata<-cbind(x1,y1,x2,y2)
distSeg(mydata)