https://github.com/cran/pracma
Tip revision: 71455748623ef69836470c75c5f9384f6e872d45 authored by HwB on 28 June 2011, 00:00:00 UTC
version 0.6-3
version 0.6-3
Tip revision: 7145574
segm_distance.Rd
\name{segm_distance}
\alias{segm_distance}
\title{
Segment Distance
}
\description{
The minimum distance between a point and a segment, or the
minimum distance between points of two segments.
}
\usage{
segm_distance(p1, p2, p3, p4 = c())
}
\arguments{
\item{p1, p2}{end points of the first segment.}
\item{p3, p4}{end points of the second segment, or the point \code{p3}
alone if \code{p4} is \code{NULL}.}
}
\details{
If \code{p4=c()}, determines the orthogonal line to the segment through
the single point and computes the distance to the intersection point.
Otherwise, it computes the distances of all four end points to the
other segment and takes the minimum of those.
}
\value{
Returns a list with component \code{l} the minimum distance and components
\code{p, q} the two nearest points.
If \code{p4=c()} then point \code{p} lies on the segment and \code{q} is
\code{p4}.
}
\author{
HwB email: <hwborchers@googlemail.com>
}
\note{
The interfaces of \code{segm_intersect} and \code{segm_distance} should be
brought into line.
}
\seealso{
\code{\link{segm_intersect}}
}
\examples{
\dontrun{
plot(c(0, 1), c(0, 1), type = "n", asp=1,
xlab = "", ylab = "", main = "Segment Distances")
grid()
for (i in 1:20) {
s1 <- matrix(runif(4), 2, 2)
s2 <- matrix(runif(4), 2, 2)
lines(s1[, 1], s1[, 2], col = "red")
lines(s2[, 1], s2[, 2], col = "darkred")
S <- segm_distance(s1[1,], s1[2,], s2[1,], s2[2,])
S$d
points(c(S$p[1], S$q[1]), c(S$p[2], S$q[2]), pch=20, col="navy")
lines(c(S$p[1], S$q[1]), c(S$p[2], S$q[2]), col="gray")
}}
}
\keyword{ geom }