recenter-methods function

Methods for Function recenter in Package `sp'

Methods for function recenter in package sp to shift or re-center geographical coordinates for a Pacific view. All longitudes < 0 are added to 360, to avoid for instance parts of Alaska being represented on the far left and right of a plot because they have values straddling 180 degrees. In general, using a projected coordinate reference system is to be preferred, but this method permits a geographical coordinate reference system to be used. This idea was suggested by Greg Snow, and corresponds to the two world representations in the maps package. methods

Methods

• obj = "SpatialPolygons": recenter a SpatialPolygons object
• obj = "Polygons": recenter a Polygons object
• obj = "Polygon": recenter an Polygon object
• obj = "SpatialLines": recenter a SpatialLines object
• obj = "Lines": recenter a Lines object
• obj = "Line": recenter an Line object

Examples

crds <- matrix(c(179, -179, -179, 179, 50, 50, 52, 52), ncol=2)
SL <- SpatialLines(list(Lines(list(Line(crds)), "1")),
 CRS("+proj=longlat +ellps=WGS84"))
bbox(SL)
SLr <- recenter(SL)
bbox(SLr)
rcrds <- rbind(crds, crds[1,])
SpP <- SpatialPolygons(list(Polygons(list(Polygon(rcrds)), ID="r1")),
 proj4string=CRS("+proj=longlat +ellps=WGS84"))
bbox(SpP)
SpPr <- recenter(SpP)
bbox(SpPr)
opar <- par(mfrow=c(1,2))
plot(SpP)
plot(SpPr)
par(opar)
crds <- matrix(c(-1, 1, 1, -1, 50, 50, 52, 52), ncol=2)
SL <- SpatialLines(list(Lines(list(Line(crds)), "1")),
 CRS("+proj=longlat +ellps=WGS84"))
bbox(SL)
SLr <- recenter(SL)
bbox(SLr)
rcrds <- rbind(crds, crds[1,])
SpP <- SpatialPolygons(list(Polygons(list(Polygon(rcrds)), ID="r1")),
 proj4string=CRS("+proj=longlat +ellps=WGS84"))
bbox(SpP)
SpPr <- recenter(SpP)
bbox(SpPr)
opar <- par(mfrow=c(1,2))
plot(SpP)
plot(SpPr)
par(opar)