elide-methods {maptools} | R Documentation

## Methods for Function elide in Package ‘maptools’

### Description

Methods for function `elide` to translate and disguise coordinate placing in the real world.

### Usage

    elide(obj, ...)

### Arguments

`obj` | object to be elided

`...`

other arguments:

bb

  if NULL, uses bounding box of object, otherwise the given bounding box

shift

  values to shift the coordinates of the input object; this is made ineffective by the scale argument

reflect

  reverse coordinate axes

scale

  if NULL, coordinates not scaled; if TRUE, the longer dimension is scaled to lie within [0,1] and aspect maintained; if a scalar, the output range of [0,1] is multiplied by scale

flip

  translate coordinates on the main diagonal

rotate

  default 0, rotate angle degrees clockwise around center

center

  default NULL, if not NULL, the rotation center, numeric of length two

unitsq

  logical, default FALSE, if TRUE and scale TRUE, impose unit square bounding box (currently only points)

### Value

The methods return objects of the input class object with elided coordinates; the coordinate reference system is not set. Note that if the input coordinates or centroids are in the data slot data.frame of the input object, they should be removed before the use of these methods, otherwise they will betray the input positions.

### Methods

obj = "SpatialPoints"

  elides object

obj = "SpatialPointsDataFrame"

  elides object

obj = "SpatialLines"

  elides object

obj = "SpatialLinesDataFrame"

  elides object

obj = "SpatialPolygons"

  elides object

obj = "SpatialPolygonsDataFrame"

  elides object

### Note

Rotation code kindly contributed by Don MacQueen

### Examples

    data(meuse)
    coordinates(meuse) <- c("x", "y")
    proj4string(meuse) <- CRS("+init=epsg:28992")
    data(meuse.riv)
    river_polygon <- Polygons(list(Polygon(meuse.riv)), ID="meuse")
    rivers <- SpatialPolygons(list(river_polygon))
    proj4string(rivers) <- CRS("+init=epsg:28992")
    rivers1 <- elide(rivers, reflect=c(TRUE, TRUE), scale=TRUE)
    meuse1 <- elide(meuse, bb=bbox(rivers), reflect=c(TRUE, TRUE), scale=TRUE)
    opar <- par(mfrow=c(1,2))
    plot(rivers, axes=TRUE)
    plot(meuse, add=TRUE)
    plot(rivers1, axes=TRUE)
    plot(meuse1, add=TRUE)
    par(opar)
    meuse1 <- elide(meuse, shift=c(10000, -10000))
    bbox(meuse)
    bbox(meuse1)
    rivers1 <- elide(rivers, shift=c(10000, -10000))
    bbox(rivers)
    bbox(rivers1)
    meuse1 <- elide(meuse, rotate=-30, center=apply(bbox(meuse), 1, mean))
    bbox(meuse)
    bbox(meuse1)
    plot(meuse1, axes=TRUE)

[Package maptools version 0.9-2 Index]