pathmapping (version 1.0.2)

DistancePointSegment:

Description

Compute distance between a point and a segment

Usage

DistancePointSegment(px, py, x1, y1, x2, y2)

Arguments

px

x coordinate of point

py

y coordinate of point

x1

x coordinate of one end of segment

y1

y coordinate of one end of segment

x2

x coordinate of other end of segment

y2

y coordinate of other end of segment

Value

returns a scalar value measuring the distance

Details

Computes the distance between a point and a segment via the shortest line. This line will be perpendicular to the segment if the point opposes the line, or it will be attached directly to an endpoint.

References

See Mueller et al., (2016). https://sites.google.com/a/mtu.edu/mapping/

See Also

LineMagnitude,ClosestPoint

Examples

##select a random point and find its closest point
##on the segment.
x1 <- runif(1)*20
y1 <- runif(1)*20

s1x <- 5;s1y <- 5
s2x <- 0;s2y <- 15

d <- DistancePointSegment(x1,y1,s1x,s1y,s2x,s2y)
plot(c(s1x,s2x),c(s1y,s2y),pch=16,xlab="x",ylab="y",
      ylim=c(-1,20),xlim=c(-1,20),type="o")
points(x1,y1,col="red",pch=16,cex=2)

p2 <-  ClosestPoint(x1,y1,s1x,s1y,s2x,s2y)
segments(p2[1],p2[2],x1,y1,lty=3)
text(10,2,paste("Distance from line to point:",
       round(d,3)))