DistancePointSegment: Compute distance between a point and a segment
In pathmapping: Compute Deviation and Correspondence Between Spatial Paths

Description Usage Arguments Details Value Author(s) References See Also Examples

Compute distance between a point and a segment

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

`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

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.

returns a scalar value measuring the distance

Shane T. Mueller and Brandon Perelman

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

LineMagnitude,ClosestPoint

##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)))