spTransform-methods          package:rgdal          R Documentation

_M_e_t_h_o_d_s _f_o_r _F_u_n_c_t_i_o_n _s_p_T_r_a_n_s_f_o_r_m _i_n _p_a_c_k_a_g_e "_r_g_d_a_l"

_D_e_s_c_r_i_p_t_i_o_n:

     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.

_M_e_t_h_o_d_s:


     "_A_N_Y" default void method

     "_S_p_a_t_i_a_l_P_o_i_n_t_s", _C_R_S_o_b_j = _C_R_S returns transformed coordinates of
          an "SpatialPoints" object using the projection arguments in
          "CRSobj", of class CRS

     "_S_p_a_t_i_a_l_P_o_i_n_t_s_D_a_t_a_F_r_a_m_e", _C_R_S_o_b_j = _C_R_S returns transformed
          coordinates of an "SpatialPointsDataFrame" object using the
          projection arguments in "CRSobj", of class CRS

     "_S_p_a_t_i_a_l_L_i_n_e_s", _C_R_S_o_b_j = _C_R_S returns transformed coordinates of an
          "SpatialLines" object using the projection arguments in
          "CRSobj", of class CRS

     "_S_p_a_t_i_a_l_L_i_n_e_s_D_a_t_a_F_r_a_m_e", _C_R_S_o_b_j = _C_R_S returns transformed
          coordinates of an "SpatialLinesDataFrame" object using the
          projection arguments in "CRSobj", of class CRS

     "_S_p_a_t_i_a_l_P_o_l_y_g_o_n_s", _C_R_S_o_b_j = _C_R_S returns transformed coordinates of
          an "SpatialPolygons" object using the projection arguments in
          "CRSobj", of class CRS

     "_S_p_a_t_i_a_l_P_o_l_y_g_o_n_s_D_a_t_a_F_r_a_m_e", _C_R_S_o_b_j = _C_R_S returns transformed
          coordinates of an "SpatialPolygonsDataFrame" object using the
          projection arguments in "CRSobj", of class CRS

_N_o_t_e:

     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.

_A_u_t_h_o_r(_s):

     Roger Bivand Roger.Bivand@nhh.no

_E_x_a_m_p_l_e_s:

     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)

