Raster objects: Compute the approximate surface area of cells in an unprojected (longitude/latitude) Raster object. It is an approximation because area is computed as the height (latitudinal span) of a cell (which is constant among all cells) times the width (longitudinal span) in the (latitudinal) middle of a cell. The width is smaller at the poleward side than at the equator-ward side of a cell. This variation is greatest near the poles and the values are thus not very precise for very high latitudes.

SpatialPolygons: Compute the area of the spatial features. Works for both planar and angular (lon/lat) coordinate reference systems

```
# S4 method for RasterLayer
area(x, filename="", na.rm=FALSE, weights=FALSE, ...)
```# S4 method for RasterStackBrick
area(x, filename="", na.rm=FALSE, weights=FALSE, ...)

# S4 method for SpatialPolygons
area(x, ...)

x

Raster* or SpatialPolygons object

filename

character. Filename for the output Raster object (optional)

na.rm

logical. If `TRUE`

, cells that are `NA`

are ignored

weights

logical. If `TRUE`

, the area of each cells is divided by the total area of all cells that are not `NA`

...

additional arguments as for `writeRaster`

If `x`

is a Raster* object: RasterLayer or RasterBrick. Cell values represent the size of the cell in km2, or the relative size if `weights=TRUE`

If `x`

is a SpatialPolygons* object: area if each spatial object in squared meters if the CRS is longitude/latitude, or in squared map units (typically meter)

If `x`

is a RasterStack/Brick, a RasterBrick will be returned if `na.rm=TRUE`

. However, if `na.rm=FALSE`

, a RasterLayer is returned, because the values would be the same for all layers.

# NOT RUN { r <- raster(nrow=18, ncol=36) a <- area(r) if (require(rgdal) & require(rgeos)) { p <- shapefile(system.file("external/lux.shp", package="raster")) p$area <- round(area(p) / 10000000,1) p$area } # }