Converting UTMs to SpatialPolygons object

Here we go, I'm assuming each ring is its own simple object, and a few
other things.

id = rep(seq(1,3),each=12)
az = rep(seq(0,359,30),3)

## assume you meant to use all ids here?
d = data.frame(id,az)
d$dist = round(rnorm(36,10,3),1)
xp = function(azimuth, r){cos(((90-azimuth)*pi)/180)*r}
yp =  function(azimuth, r){sin(((90-azimuth)*pi)/180)*r}
ctr_e = rnorm(3,667314,50)
ctr_n = rnorm(3,4784480,50)

d$utm_e = round(xp(d$az,d$dist),1) + ctr_e[d$id]
d$utm_n = round(yp(d$az,d$dist),1) + ctr_n[d$id]

library(sp)
myCRS = CRS("+proj=utm +zone=18 +ellps=WGS84")

## create list of coords, including repeat of first row for each
l.coords <- lapply(split(d, d$id), function(x)
as.matrix(x[c(seq_len(nrow(x)), 1), c("utm_e", "utm_n")]))

l.Polygons <- vector("list",length(l.coords))

for (i in seq_len(length(l.coords))) {
    l.Polygons[[i]] <- Polygons(list(Polygon(l.coords[i])), as.character(i))
}

SpPolys <- SpatialPolygons(l.Polygons, proj4string = myCRS)

plot(SpPolys, col = c("grey", "red", "blue"))

Converting UTMs to SpatialPolygons object

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