spCircle: Create a Circular Spatial Object

Description

This function simply creates a circular polygon object that is of class "'>SpatialPolygons". It also creates a "'>SpatialPoints" object holding the center point of the circle.

Usage

spCircle(radius,
         spUnits = CRS(projargs = as.character(NA)),
         centerPoint = c(x = 0, y = 0),
         nptsPerimeter = 100,
         spID = paste("circle", .StemEnv$randomID(), sep = ":"),
         ...)

Arguments

radius

The radius of the circle in the appropriate units.

spUnits

Object of class "CRS": A legal proj.4 coordinate system; the default is to have user-defined coordinates.

centerPoint

The circle's center location in the appropriate units. This is a vector of length two with names "x" and "y".

nptsPerimeter

The number of points forming the perimeter of the polygon.

spID

A unique identifier that will be used in displaying the spatial polygon.

…

Not used currently.

Value

A list with the following components…

spCircle

The "'>SpatialPolygons" polygon object.

location

The "'>SpatialPoints" point object.

Details

The polygon created for the circle will always have the individual internal "'>Polygon" object named ‘pgCircle’, while the internal "'>Polygons" object will be named ‘pgsCircle’. These may need to be renamed in the returned object to make more sense. See the sp package for more details.

Examples

Run this code

# NOT RUN {
dbh = 20
sp.dbh = spCircle(dbh/2, centerPoint=c(x=30,y=80), spID='tree.1') 
plot(sp.dbh$spCircle)
plot(sp.dbh$location, add=TRUE, pch=3)
# }