calcCentroid: Calculate the Centroids of Polygons

Description Usage Arguments Details Value Author(s) See Also Examples

View source: R/PBSmapping.r

Description

Calculate the centroids of polygons found in a PolySet.

Usage

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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.

Author(s)

Nicholas M. Boers, Associate Professor – Computer Science
MacEwan University, Edmonton AB
Last modified Rd: 2013-04-10

See Also

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

Examples

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local(envir=.PBSmapEnv,expr={
  #--- load the data (if using R)
  if (!is.null(version$language) && (version$language=="R"))
    data(nepacLL,envir=.PBSmapEnv)
  #--- calculate and print the centroids for several polygons
  print(calcCentroid(nepacLL[is.element(nepacLL$PID,c(33,39,47)),]))
})

Example output

sh: 1: cannot create /dev/null: Permission denied

-----------------------------------------------------------
PBS Mapping 2.70.5 -- Copyright (C) 2003-2019 Fisheries and Oceans Canada

PBS Mapping comes with ABSOLUTELY NO WARRANTY;
for details see the file COPYING.
This is free software, and you are welcome to redistribute
it under certain conditions, as outlined in the above file.

A complete user guide 'PBSmapping-UG.pdf' is located at 
/usr/lib/R/site-library/PBSmapping/doc/PBSmapping-UG.pdf

Packaged on 2018-06-05
Pacific Biological Station, Nanaimo

All available PBS packages can be found at
https://github.com/pbs-software

To see demos, type '.PBSfigs()'.
-----------------------------------------------------------


  PID         X        Y
1  33 -125.7302 49.64381
2  39 -132.7354 55.52470
3  47 -132.2675 53.44296

PBSmapping documentation built on Jan. 15, 2021, 3:41 p.m.