R: Methods for Function recenter in Package 'sp'

recenter-methods {sp} | R Documentation

## Methods for Function recenter in Package ‘sp’

### Description

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

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)

[Package sp version 1.4-0 Index]