# R/makePoly.R In geosphere: Spherical Trigonometry

#### Documented in makeLinemakePoly

```# author Robert Hijmans
# April 2010
# version 0.1

.makeSinglePoly <- function(p, interval=10000, ...) {
res <- p[1,]
for (i in 1:(nrow(p)-1)) {
if (! isTRUE( all.equal(p[i,], p[i+1,]) )) {
d <- distGeo(p[i,], p[i+1,], ...)
n <- floor(d / interval)
if (n > 0) {
pts <- gcIntermediate(p[i,],p[i+1,], n)
pts <- rbind(p[i,], pts, p[i+1,])
res <- rbind(res, pts, p[i+1,])
} else {
res <- rbind(res, p[i+1,])
}
}
}
if (nrow(res) < 3) stop('cannot make a valid polygon')
return(res)
}

.makeSingleLine <- function(p, interval=10000, ...) {
res <- p[1,]
for (i in 1:(nrow(p)-1)) {
if (! isTRUE( all.equal(p[i,], p[i+1,]) )) {
d <- distGeo(p[i,], p[i+1,], ...)
n <- floor(d / interval)
if (n > 0) {
pts <- gcIntermediate(p[i,],p[i+1,], n)
pts <- rbind(p[i,], pts, p[i+1,])
res <- rbind(res, pts, p[i+1,])
} else {
res <- rbind(res, p[i+1,])
}
}
}
if (nrow(res) < 2) stop('cannot make a valid line')
return(res)
}

makePoly <- function(p, interval=10000, sp=FALSE, ...) {
if (inherits(p, 'SpatialPolygons')) {
test <- !is.projected(p)
if (! isTRUE (test) ) {
if (is.na(test)) {
warning('Coordinate reference system of SpatialPolygons object is not set. Assuming it is degrees (longitude/latitude)!')
} else {
stop('Points are projected. They should be in degrees (longitude/latitude)')
}
# or rather transform them ....?
}

x <- p@polygons
n <- length(x)
polys = list()
for (i in 1:n) {
parts <- length(x[[i]]@Polygons )
partlist <- list()
for (j in 1:parts) {
crd <- x[[i]]@Polygons[[j]]@coords
crd <- .makeSinglePoly(crd, interval=interval, ...)
partlist[[j]] <- Polygon(crd)
}
polys[[i]] <- Polygons(partlist, i)
}
polys <- SpatialPolygons(polys)
if (inherits(p, 'SpatialPolygonsDataFrame')) {
rownames(p@data) <- 1:nrow(p@data)
polys <- SpatialPolygonsDataFrame(polys, p@data)
}
polys@proj4string <- p@proj4string
return(polys)
} else {
p <- .pointsToMatrix(p)
if (nrow(p) < 3) {
stop('cannot make a polygon (insufficent number of vertices)')
}
if (! isTRUE(all.equal(p[1,], p[nrow(p),]))) {
p <- rbind(p, p[1,])
}
res <- .makeSinglePoly(p, interval=interval, ...)
if (sp) {
res <- SpatialPolygons(list(Polygons(list(Polygon(res)), 1)))
res@proj4string <- CRS("+proj=longlat +datum=WGS84")
}
return(res)
}
}

makeLine <- function(p, interval=10000, sp=FALSE, ...) {
if (inherits(p, 'SpatialLines')) {
test <- !is.projected(p)
if (! isTRUE (test) ) {
if (is.na(test)) {
warning('Coordinate reference system of SpatialPolygons object is not set. Assuming it is degrees (longitude/latitude)!')
} else {
stop('Points are projected. They should be in degrees (longitude/latitude)')
}
# or rather transform them ....?
}

x = p@lines
n = length(x)
lines = list()
for (i in 1:n) {
parts = length(x[[i]]@Lines )
partlist = list()
for (j in 1:parts) {
crd = x[[i]]@Lines[[j]]@coords
crd = .makeSingleLine(crd, interval=interval, ...)
partlist[[j]] = Line(crd)
}
lines[[i]] = Lines(partlist, i)
}
lines <- SpatialLines(lines)
if (inherits(p, 'SpatialLinesDataFrame')) {
lines <- SpatialLinesDataFrame(lines, p@data)
}
lines@proj4string <- p@proj4string
return(lines)
} else {
p <- .pointsToMatrix(p)
if (nrow(p) < 3) {
stop('cannot make a polygon (insufficent number of vertices)')
}
res <- .makeSingleLine(p, interval=interval, ...)
if (sp) {
res <- SpatialLines(list(Lines(list(Line(res)), 1)))
res@proj4string <- CRS("+proj=longlat +datum=WGS84")
}
return(res)
}
}
```

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geosphere documentation built on July 21, 2018, 3 p.m.