1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
degreeLabelsNS = function(x) {
pos = sign(x) + 2
dir = c("*S", "", "*N")
paste(abs(x), "*degree", dir[pos])
}
degreeLabelsEW = function(x) {
x <- ifelse(x > 180, x - 360, x)
pos = sign(x) + 2
if (any(x == -180))
pos[x == -180] = 2
if (any(x == 180))
pos[x == 180] = 2
dir = c("*W", "", "*E")
paste(abs(x), "*degree", dir[pos])
}
gridlines = function(x, easts = pretty(bbox(x)[1,]),
norths = pretty(bbox(x)[2,]), ndiscr = 20)
{
bb = bbox(x)
easts <- easts[easts > bb[1,1] & easts < bb[1,2]]
eastlist <- vector(mode="list", length=length(easts))
for (i in 1:length(easts))
eastlist[[i]] <- Line(cbind(rep(easts[i], ndiscr),
seq(bb[2,1], bb[2,2], length.out=ndiscr)))
norths <- norths[norths > bb[2,1] & norths < bb[2,2]]
northlist <- vector(mode="list", length=length(norths))
for (i in 1:length(norths))
northlist[[i]] <- Line(cbind(seq(bb[1,1], bb[1,2], length.out=ndiscr),
rep(norths[i], ndiscr)))
SpatialLines(list(Lines(northlist, "NS"), Lines(eastlist, "EW")),
CRS(proj4string(x)))
}
gridat <- function(x, easts = pretty(bbox(x)[1,]),
norths = pretty(bbox(x)[2,]), offset=0.5)
{
isp = is.projected(x)
if (is.na(isp) || isp) stop("x must not be projected")
bb = bbox(x)
easts <- easts[easts > bb[1,1] & easts < bb[1,2]]
norths <- norths[norths > bb[2,1] & norths < bb[2,2]]
a1 <- cbind(easts, rep(bb[2,1], length(easts)))
a1lab <- degreeLabelsEW(a1[,1])
a2 <- cbind(rep(bb[1,1], length(norths)), norths)
a2lab <- degreeLabelsNS(a2[,2])
as <- SpatialPoints(rbind(a1, a2), CRS(proj4string(x)))
res <- SpatialPointsDataFrame(as,
data.frame(
#AttributeList(list(
labels = c(a1lab, a2lab),
pos = c(rep(1, length(easts)), rep(2, length(norths))),
offset = rep(offset, length(easts)+length(norths))
)
#)
)
res
}
|
