Methods for "circularPlot" Object Construction in package ‘sampSurf’


There is currently only one method based on the circularPlot generic that is used for object construction. It is detailed below.


signature(radius = "numeric")

This method takes the plot radius as the signature argument along with other optional aruments described as follows...


             units = 'metric',
             spUnits = CRS(projargs=as.character(NA)),
             centerPoint = c(x=0, y=0),  
             description = 'fixed area circular plot',
             nptsPerimeter = 100,
             spID = unlist(strsplit(tempfile('cp:',''),'\/'))[2],
  • radius: The fixed-plot radius in the correct units. For "English" units, this would be feet, for "metric" units, meters.

  • units: Either “English” or “metric”. These must be conformable with the projection in spUnits.

  • spUnits: A valid CRS object specifying the Coordinate Reference System. This defaults to NA, which means you want to use your own user-defined system, say for a sample plot located in the field.

  • centerPoint: The location of the center of the fixed-area plot in the appropriate spatial units. This should be a numeric vector of length 2 with names "x" and "y".

  • description: A character vector description of the tract.

  • nptsPerimeter: The number of points that will compose the spatial perimeter of the object. Note that the final result will always be one more point than requested in order to close the polygon.

  • spID: Each object should have its own unique identifier that is used in constructing the Polygons object for the perimeter. This becomes very important when combining individual plots into a population. If nothing is supplied, a random ID is generated.

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