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#
# fields is a package for analysis of spatial data written for
# the R software environment.
# Copyright (C) 2024 Colorado School of Mines
# 1500 Illinois St., Golden, CO 80401
# Contact: Douglas Nychka, douglasnychka@gmail.com,
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with the R software environment if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
# or see http://www.r-project.org/Licenses/GPL-2
##END HEADER
fields.rdist.near <- function(x1, x2, delta, max.points = NULL,
mean.neighbor = 50) {
if (!is.matrix(x1))
x1 <- as.matrix(x1)
if (missing(x2))
x2 <- x1
if (!is.matrix(x2))
x2 <- as.matrix(x2)
d <- ncol(x1)
n1 <- nrow(x1)
n2 <- nrow(x2)
if (is.null(max.points)) {
Nmax <- n1 * mean.neighbor
}
else {
Nmax <- max.points
}
out <- .Fortran("ddfind",PACKAGE="fields",
nd = as.integer(d), x1 = as.double(x1),
n1 = as.integer(n1), x2 = as.double(x2), n2 = as.integer(n2),
D0 = as.double(delta), ind = as.integer(rep(0, Nmax *
2)), rd = as.double(rep(-1, Nmax)), Nmax = as.integer(Nmax),
iflag = as.integer(1))
N <- out$Nmax
if (out$iflag == -1) {
cat("temp space set at", Nmax, fill = TRUE)
stop("Ran out of space, increase max.points")
}
return(list(ind = matrix(out$ind, Nmax, 2)[1:N, ], ra = out$rd[1:N],
da = c(n1, n2)))
}
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