Revision d50cda4811eb3cdb8d2ce9e01ddb5e07d4a8c24f authored by HwB on 11 September 2013, 00:00:00 UTC, committed by Gabor Csardi on 11 September 2013, 00:00:00 UTC
1 parent 10ae2bb
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}.
}
\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 }
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