Shape (spatial object) specification

Specify a shape, which is a spatial object from one of these spatial object class packages: sf, stars, or terra.

Usage

tm_shape(
  shp = NULL,
  bbox = NULL,
  crs = NULL,
  is.main = NA,
  name = NULL,
  unit = NULL,
  filter = NULL,
  ...
)

Arguments

shp: Spatial object
bbox: Bounding box of the map (only used if shp is the main shape (see is.main)
crs: Map projection (CRS). Can be set to an crs object (see sf::st_crs()), a proj4string, an EPSG number, the value "auto" (automatic crs recommendation), or one the the following generic projections: c("laea", "aeqd", "utm", "pconic", "eqdc", "stere"). See details.
is.main: Is shp the main shape, which determines the crs and bounding box of the map? By default, TRUE if it is the first tm_shape call
name: of the spatial object
unit: Unit of the coordinates
filter: Filter features
...: passed on to bb (e.g. ext can be used to enlarge or shrink a bounding box)

Details

The map projection (crs) determines in which coordinate system the spatial object is processed and plotted. See vignette about CRS. The crs can be specified in two places: 1) tm_shape() and tm_crs(). In both cases, the map is plotted into the specified crs. The difference is that in the first option, the crs is also taken into account in spatial transformation functions, such as the calculation of centroids and cartograms. In the second option, the crs is only used in the plotting phase.

The automatic crs recommendation (which is still work-in-progress) is the following:

Property	Recommendation
`global` (for world maps)	A pseudocylindrical projection tmap option `crs_global`, by default `"eqearth` (Equal Earth). See https://r-tmap.github.io/tmap/articles/41_advanced_crs.html for more options
`area` (equal area)	Lambert Azimuthal Equal Area (`laea`)
`distance` (equidistant)	Azimuthal Equidistant (`aeqd`)
`shape` (conformal)	Stereographic (`stere`)

For further info about the available "generic" projects see: for utm: https://proj.org/en/9.4/operations/projections/utm.html for laea: https://proj.org/en/9.4/operations/projections/laea.html for aeqd: https://proj.org/en/9.4/operations/projections/aeqd.html for pconic: https://proj.org/en/9.4/operations/projections/pconic.html for eqdc: https://proj.org/en/9.4/operations/projections/eqdc.html

Note

as of tmap 4.0, simplify has been removed. Please use tmaptools::simplify_shape() instead

Examples

tm_shape(World, crs = "auto") +
  tm_polygons()


tm_shape(World, crs = 3035, bb = "Europe") +
  tm_polygons()


tm_shape(World, crs = "+proj=robin", filter = World$continent=="Africa") +
  tm_polygons()