calcConvexHull: Calculate the Convex Hull for a Set of Points

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

View source: R/PBSmapping.r

Description

Calculate the convex hull for a set of points.

Usage

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calcConvexHull (xydata, keepExtra=FALSE)

Arguments

xydata

a data frame with columns X and Y containing spatial coordinates.

keepExtra

logical: if TRUE, retain any additional columns from the input data frame xydata.

Details

This routine uses the function chull() in the package grDevices. By default, it ignores all columns other than X and Y; however, the user can choose to retain additional columns in xydata by specifying keepExtra=TRUE.

Value

PolySet with columns PID, POS, X, Y, and additional columns in xydata if keepExtra=TRUE.

Author(s)

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

See Also

addPoints, addPolys, calcArea, calcCentroid, calcMidRange, calcSummary, locateEvents, plotMap, plotPoints, plotPolys.

Examples

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local(envir=.PBSmapEnv,expr={
  oldpar = par(no.readonly=TRUE)
  data(surveyData,envir=.PBSmapEnv)
  #--- plot the convex hull, and then plot the points
  plotMap(calcConvexHull(surveyData),col="moccasin")
  addPoints(surveyData,col="blue",pch=17,cex=.6)
  par(oldpar)
})

Example output

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

-----------------------------------------------------------
PBS Mapping 2.70.4 -- Copyright (C) 2003-2017 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 2017-06-28
Pacific Biological Station, Nanaimo

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

To see demos, type '.PBSfigs()'.
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PBSmapping documentation built on Jan. 15, 2021, 3:41 p.m.