R/mindist.polygon.R

In baddstats/spherstat: Spatial Point Pattern Analysis, Geometry and Trigonometry for the Sphere

 mindist.polygon <- function (X, win) 
{
    stopifnot(inherits(X, c("sp2", "sp3", "matrix")))
    if (inherits(X, "matrix")) {
        stopifnot(inherits(win, "sphwin"))
    }
    else {
        win <- X$win
        X <- X$X
    }
    rad <- win$rad
    nX <- nrow(X)
    if (nX == 0) 
        return(Inf)
    if (ncol(X) != 3) {
        X <- convert3(X)
    }
    verts <- convert3(win$param)
    nvert <- nrow(verts)
    dXV <- gcdist(x = X, y = verts, rad = rad)
    dXVj <- t(dXV[, -nvert, drop = FALSE])
    dXVjplus1 <- t(dXV[, -1, drop = FALSE])
    elen <- gcdistPaired(x = verts[-nvert, , drop = FALSE], y = verts[-1, 
        , drop = FALSE], rad = rad)
    ang1 <- sphcos(d1 = dXVj, d2 = elen, d3 = dXVjplus1, theta = NULL, 
        rad = rad)
    ang2 <- sphcos(d1 = dXVjplus1, d2 = elen, d3 = dXVj, theta = NULL, 
        rad = rad)
    perps <- sphsin(d1 = dXVj, d2 = NULL, theta1 = pi/2, theta2 = ang1, 
        rad = rad)
    dists <- ifelse(ang1 < pi/2 & ang2 < pi/2, perps, pmin(dXVj, 
        dXVjplus1))
    md <- if (!is.matrix(dists)) 
        min(dists)
    else apply(dists, 2, min)
    return(md)
}