sp_area: Function to calculate areas of spatial polygons in...
In skgrange/gissr: Tools To Make Working With R and Spatial Data Easier

sp_area

R Documentation

Function to calculate areas of spatial polygons in metres-squared, kilometres-squared, or hectares.

Description

If the spatial-polygons are projected in a system with a metre unit, rgeos::gArea is used to calculate the area of the polygons. If the projection system is WGS84, a trigonometric function is used (geosphere::areaPolygon). Although using a projection system with metres yields the most accurate results, the geosphere::areaPolygon function has been tested and performs well.

Usage

sp_area(sp, unit = "m", features = TRUE)

Arguments

`sp`	Spatial-polygons object.
`unit`	Unit of returned area. Can be "m", "km", or "ha". Default is "m".
`features`	Should the individual areas of the features contained within `sp` be calculated? Default is `TRUE`.

Author(s)

Stuart K. Grange

Examples

## Not run: 
# Calculate the area of the Greater London Built-up area, sp is projected 
in OSGB36, a metric projection system

sp_area(sp_built_up_london, unit = "km")
1737.855

# Wikipedia says the same
# https://en.wikipedia.org/wiki/Greater_London_Built-up_Area

## End(Not run)

skgrange/gissr documentation built on Feb. 24, 2024, 2:55 p.m.