fixBound: Fix the Boundary Points of a PolySet

In PBSmapping: Mapping Fisheries Data and Spatial Analysis Tools

Fix the Boundary Points of a PolySet

Description

The ranges of a PolySet's X and Y columns define its boundary. This function fixes a PolySet's vertices by moving vertices near a boundary to the actual boundary.

Usage

fixBound (polys, tol)

Arguments

polys	PolySet to fix.
tol	vector (length 1 or 2) specifying a percentage of the ranges to use in defining near to a boundary. If tol has two elements, the first specifies the tolerance for the x-axis and the second the y-axis. If it has only one element, the function uses the same tolerance for both axes.

Details

When moving vertices to a boundary, the function moves them strictly horizontally or vertically, as appropriate.

Value

PolySet identical to the input, except for possible changes in the X and Y columns.

Author(s)

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

See Also

closePolys, fixPOS, isConvex, isIntersecting, PolySet.

Examples

local(envir=.PBSmapEnv,expr={
  oldpar = par(no.readonly=TRUE)
  #--- set up a long horizontal and long vertical line to extend the plot's
  #--- limits, and then try fixing the bounds of a line in the top-left
  #--- corner and a line in the bottom-right corner
  polys <- data.frame(PID=c(1, 1, 2, 2,  3, 3, 4, 4),
    POS=c(1, 2, 1, 2,  1, 2, 1, 2),
    X = c(0, 10, 5, 5, 0.1, 4.9, 5.1, 9.9),
    Y = c(5, 5, 0, 10, 5.1, 9.9, 0.1, 4.9))
  polys <- fixBound(polys, tol=0.0100001)
  plotLines(polys)
  par(oldpar)
})

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