convCP: Convert Contour Lines into a PolySet

In PBSmapping: Mapping Fisheries Data and Spatial Analysis Tools

Convert Contour Lines into a PolySet

Description

Convert output from contourLines into a PolySet.

Usage

convCP (data, projection = NULL, zone = NULL)

Arguments

data	contour line data, often from the contourLines function.
projection	optional projection attribute to add to the PolySet.
zone	optional zone attribute to add to the PolySet.

Details

data contains a list as described below. The contourLines function create a list suitable for the data argument.

A three-element list describes each contour. The named elements in this list include the scalar level, the vector x, and the vector y. Vectors x and y must have equal lengths. A higher-level list (data) contains one or more of these contours lists.

Value

A list with two named elements PolySet and PolyData. The PolySet element contains a PolySet representation of the contour lines. The PolyData element links each contour line (PID, SID) with a level.

Author(s)

Nicholas M. Boers, Staff Software Engineer
Jobber, Edmonton AB
Last modified Rd: 2013-04-10

See Also

contour, contourLines, convLP, makeTopography.

Examples

local(envir=.PBSmapEnv,expr={
  oldpar = par(no.readonly=TRUE)
  #--- create sample data for the contourLines() function
  x <- seq(-0.5, 0.8, length=50);  y <- x
  z <- outer(x, y, FUN = function(x,y) { sin(2*pi*(x^2+y^2))^2; } )
  data <- contourLines(x, y, z, levels=c(0.2, 0.8))
  #--- pass that sample data into convCP()
  result <- convCP(data)
  #--- plot the result
  plotLines(result$PolySet, projection=1)
  print(result$PolyData)
  par(oldpar)
})

PBSmapping documentation built on Sept. 30, 2024, 9:21 a.m.