rgdal (version 0.4-4)

spTransform-methods: Methods for Function spTransform in package "rgdal"

Description

Transformation in package "sp" is concerned with transformation between datum(s) and conversion between projections, from one unambiguously specified coordinate reference system to another, using PROJ.4 projection arguments. Note that warnings about different projections may be issued when the PROJ.4 library extends projection arguments; examine the warning to see if the differences are real.

Examples

data(state)
states <- data.frame(state.x77, state.center)
states <- states[states$x > -121,]
coordinates(states) <- c("x", "y")
proj4string(states) <- CRS("+proj=longlat +ellps=clrk66")
summary(states)
state.ll83 <- spTransform(states, CRS("+proj=longlat +ellps=GRS80"))
summary(state.ll83)
state.merc <- spTransform(states, CRS=CRS("+proj=merc +ellps=GRS80"))
summary(state.merc)
state.merc <- spTransform(states, CRS=CRS("+proj=merc +ellps=GRS80 +units=us-mi"))
summary(state.merc)
states <- data.frame(state.x77, state.center)
states <- states[states$x > -121,]
coordinates(states) <- c("x", "y")
proj4string(states) <- CRS("+init=epsg:4267")
summary(states)
state.ll83 <- spTransform(states, CRS("+init=epsg:4269"))
summary(state.ll83)
state.kansasSlcc <- spTransform(states, CRS=CRS("+init=epsg:26978"))
summary(state.kansasSlcc)
data(meuse)
coordinates(meuse) <- c("x", "y")
proj4string(meuse) <- CRS("+proj=stere +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.999908 +x_0=155000 +y_0=463000 +ellps=bessel +units=m")
summary(meuse)
meuse.utm <- spTransform(meuse, CRS("+proj=utm +zone=32 +ellps=WGS84"))
summary(meuse.utm)
cbind(coordinates(meuse), coordinates(meuse.utm))
kiritimati_primary_roads <- readOGR(system.file("vectors", package = "rgdal")[1], "kiritimati_primary_roads")
kiritimati_primary_roads_ll <- spTransform(kiritimati_primary_roads, CRS("+proj=longlat +ellps=WGS84"))
opar <- par(mfrow=c(1,2))
plot(kiritimati_primary_roads, axes=TRUE)
plot(kiritimati_primary_roads_ll, axes=TRUE, las=1)
par(opar)
scot_BNG <- readOGR(system.file("vectors", package = "rgdal")[1], "scot_BNG")
scot_LL <- spTransform(scot_BNG, CRS("+proj=longlat +datum=WGS84"))
opar <- par(mfrow=c(1,2))
plot(scot_LL, axes=TRUE)
plot(scot_BNG, axes=TRUE, las=1)
toproj <- CRS(proj4string(scot_BNG))
easts <- pretty(bbox(scot_LL)[1,], min.n=4)
easts <- easts[easts > bbox(scot_LL)[1,1] & easts < bbox(scot_LL)[1,2]]
eastlist <- vector(mode="list", length=length(easts))
for (i in 1:length(easts)) eastlist[[i]] <- Line(cbind(rep(easts[i], 100), seq(bbox(scot_LL)[2,1], bbox(scot_LL)[2,2], length.out=100)))
plot(spTransform(SpatialLines(list(Lines(eastlist)), CRS("+proj=longlat +datum=WGS84")), toproj), add=TRUE, col="grey")
norths <- pretty(bbox(scot_LL)[2,], min.n=4)
norths <- norths[norths > bbox(scot_LL)[2,1] & norths < bbox(scot_LL)[2,2]]
northlist <- vector(mode="list", length=length(norths))
for (i in 1:length(norths)) northlist[[i]] <- Line(cbind(seq(bbox(scot_LL)[1,1], bbox(scot_LL)[1,2], length.out=100), rep(norths[i], 100)))
plot(spTransform(SpatialLines(list(Lines(northlist)), CRS("+proj=longlat +datum=WGS84")), toproj), add=TRUE, col="grey")
par(opar)