in.out

0th

Percentile

Which of a set of points lie within a polygon defined region

Tests whether each of a set of points lie within a region defined by one or more (possibly nested) polygons. Points count as `inside' if they are interior to an odd number of polygons.

Usage
in.out(bnd,x)
Arguments
bnd
A two column matrix, the rows of which define the vertices of polygons defining the boundary of a region. Different polygons should be separated by an NA row, and the polygons are assumed closed.
x
A two column matrix. Each row is a point to test for inclusion in the region defined by bnd.
Details

The algorithm works by counting boundary crossings (using compiled C code).

Value

nrow(x). TRUE if the corresponding row of x is inside the boundary and FALSE otherwise.

References

http://www.maths.bris.ac.uk/~sw15190/

Aliases
  • in.out
Examples
library(mgcv) library(mgcv) data(columb.polys) bnd <- columb.polys[[2]] plot(bnd,type="n") polygon(bnd) x <- seq(7.9,8.7,length=20) y <- seq(13.7,14.3,length=20) gr <- as.matrix(expand.grid(x,y)) inside <- in.out(bnd,gr) points(gr,col=as.numeric(inside)+1)
Documentation reproduced from package mgcv, version 1.8-16, License: GPL (>= 2)

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