spTransform-methods {rgdal} | R Documentation

## 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.

### Methods

"ANY"
  default void method
"SpatialPoints", CRSobj = CRS
  returns transformed coordinates of an "SpatialPoints" object using the projection arguments in "CRSobj", of class CRS
"SpatialPointsDataFrame", CRSobj = CRS
  returns transformed coordinates of an "SpatialPointsDataFrame" object using the projection arguments in "CRSobj", of class CRS
"SpatialLines", CRSobj = CRS
  returns transformed coordinates of an "SpatialLines" object using the projection arguments in "CRSobj", of class CRS
"SpatialLinesDataFrame", CRSobj = CRS
  returns transformed coordinates of an "SpatialLinesDataFrame" object using the projection arguments in "CRSobj", of class CRS
"SpatialPolygons", CRSobj = CRS
  returns transformed coordinates of an "SpatialPolygons" object using the projection arguments in "CRSobj", of class CRS
"SpatialPolygonsDataFrame", CRSobj = CRS
  returns transformed coordinates of an "SpatialPolygonsDataFrame" object using the projection arguments in "CRSobj", of class CRS

### Note

The projection arguments must be entered exactly as in the PROJ.4 documentation, in particular there cannot be any white space in +<arg>=<value> strings, and successive such strings can only be separated by blanks.

### Author(s)

Roger Bivand Roger.Bivand@nhh.no

### Examples

    data(state)
    states <- data.frame(state.x77, state.center)
    states <- states[states$x > -121,]
    coordinates(states) <- c("x", "y")
    proj4string(states) <- CRS("+proj=longlat +ellps=clrk66")
    summary(states)
    state.ll83 <- spTransform(states, CRS("+proj=longlat +ellps=GRS80"))
    summary(state.ll83)
    state.merc <- spTransform(states, CRS=CRS("+proj=merc +ellps=GRS80"))
    summary(state.merc)
    state.merc <- spTransform(states, CRS=CRS("+proj=merc +ellps=GRS80 +units=us-mi"))
    summary(state.merc)
    ## Not run:
    states <- data.frame(state.x77, state.center)
    states <- states[states$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)
    ## End(Not run)
    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)

[Package rgdal version 0.4-4 Index]