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.SP2owin <- function(SP) {
require(spatstat)
pls <- slot(SP, "polygons")
nParts <- sapply(pls, function(x) length(slot(x, "Polygons")))
nOwin <- sum(nParts)
if (nOwin == 1) {
pl <- slot(pls[[1]], "Polygons")
crds <- slot(pl[[1]], "coords")
colnames(crds) <- c("x", "y")
rD <- pl[[1]]@ringDir
if (rD == 1) crds <- crds[nrow(crds):1,]
crds <- crds[-nrow(crds),]
res <- owin(poly=list(x=crds[,1], y=crds[,2]))
} else if (nOwin > 1) {
opls <- vector(mode="list", length=nOwin)
io <- 1
for (i in seq(along=pls)) {
pl <- slot(pls[[i]], "Polygons")
for (j in 1:nParts[i]) {
crds <- slot(pl[[j]], "coords")
colnames(crds) <- c("x", "y")
rD <- slot(pl[[j]], "ringDir") # sp:::.spFindCG(crds)$rD
hole <- slot(pl[[j]], "hole")
if (rD == -1 && hole) crds <- crds[nrow(crds):1,]
else if (rD == 1 && !hole) crds <- crds[nrow(crds):1,]
crds <- crds[-nrow(crds),]
opls[[io]] <- list(x=crds[,1], y=crds[,2])
io <- io+1
}
}
# if (exists(".spatstat_check") && !.spatstat_check)
if (!spatstat.options("checkpolygons"))
res <- owin(bbox(SP)[1,], bbox(SP)[2,], poly = opls,
check=FALSE)
# 070718 added check avoidance
else res <- owin(poly=opls)
} else stop("no valid polygons")
res
}
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