calcCentroid {PBSmapping}R Documentation

Calculate the Centroids of Polygons

Description

Calculates the centroids of polygons found in a PolySet.

Usage

calcCentroid (polys, rollup = 3)

Arguments

polys PolySet to use.
rollup level of detail in the results; 1 = PIDs only, 2 = outer contours only, and 3 = no roll-up. When rollup equals 1 and 2, the function appropriately adjusts for polygons with holes.

Details

If rollup equals 1, the results contain a centroid for each unique PID only. When it equals 2, they contain entries for outer contours only. Finally, setting it to 3 prevents roll-up, and they contain a centroid for each unique (PID, SID).

Value

PolyData with columns PID, SID (may be missing), X, and Y.

See Also

calcArea, calcLength, calcMidRange, calcSummary, locateEvents, locatePolys.

Examples

#--- load the data (if using R)
if (!is.null(version$language) && (version$language == "R"))
  data(nepacLL)
#--- calculate and print the centroids for several polygons
print(calcCentroid(nepacLL[is.element(nepacLL$PID, c(33, 39, 47)), ]))
[Package PBSmapping version 2.09 Index]