is.projected: Sets or retrieves projection attributes on classes extending...

In sp: Classes and Methods for Spatial Data

Sets or retrieves projection attributes on classes extending SpatialData

Description

Sets or retrieves projection attributes on classes extending SpatialData; set or retrieve option value for error or warning on exceedance of geographical coordinate range, set or retrieve option value for exceedance tolerance of geographical coordinate range. Note that only “+proj=longlat +ellps=WGS84” is accepted for geographical coordinates, which must be ordered (eastings, northings); the “+ellps=” definition must be given (or expanded internally from a given “+datum=” value) for recent versions of the PROJ library, and should be set to an appropriate value.

From release 6 of the PROJ library, when used in building rgdal with GDAL >= 3, the +datum= key in the Proj.4 string CRS representation is deprecated, and the +towgs84= and +nadgrids= keys may be deprecated soon. For this reason, sp, rgdal and sf are starting to use WKT2 (2019) string representations. In sp, the "CRS" object in itself remains unchanged, but the content of its "projargs" slot may be degraded. To work around the degradation, a comment is added around the "CRS" object containing a WKT2 (2019) string when rgdal is available and built with PROJ >= 6 and GDAL >=3. The wkt() accessor function returns the WKT2 (2019) string comment belonging to the "CRS" object.

Usage

is.projected(obj)
proj4string(obj)
proj4string(obj) <- value
wkt(obj)
get_ll_warn()
get_ll_TOL()
get_ReplCRS_warn()
set_ll_warn(value)
set_ll_TOL(value)
set_ReplCRS_warn(value)

Arguments

obj

An object of class or extending Spatial-class

value

For proj4string CRS object, containing a valid proj4 string; attempts to assign an object containing “longlat” to data extending beyond longitude [-180, 360] or lattitude [-90, 90] will be stopped. For set_ll_warn a single logical value, if FALSE (default) error on range exceedance, if TRUE, warning. For set_ll_TOL the value of the power of .Machine$double.eps (default 0.25) to use as tolerance in testing range exceedance. set_ReplCRS_warn may be used to turn off warnings issued when changing object CRS with the proj4string replacement method (by setting value=FALSE).

Details

proj4 strings are operative through CRAN package rgdal. For strings defined as “longlat”, the minimum longitude should be -180, the maximum longitude 360, the minimum latitude -90, and the maximum latitude 90. Note that the proj4string replacement method does not project spatial data - for this use spTransform methods in the rgdal package.

Value

is.projected returns a logical that may be NA; proj4string returns a character vector of length 1.

Author(s)

Edzer Pebesma, [e-mail]

See Also

CRS

Examples

o <- new("Spatial")
proj4string(o) <- CRS("+init=epsg:27700")
if (!is.null(comment(slot(o, "proj4string")))) {
  cat(strsplit(wkt(o), "\n")[[1]], sep="\n")
  cat(strsplit(wkt(slot(o, "proj4string")), "\n")[[1]], sep="\n")
}
is.projected(CRS("+proj=longlat"))
is.projected(CRS("+proj=geocent"))
is.projected(CRS("+proj=geocent +units=km"))

sp documentation built on May 29, 2024, 5:33 a.m.