Coordinates of Points Inside a Polygon
This function builds a rectangular grid and extracts points which are inside of an internal polygonal region.
polygrid(xgrid, ygrid, borders, vec.inout = FALSE, ...)
xgrid |
grid values in the x-direction. |
ygrid |
grid values in the y-direction. |
borders |
a matrix with polygon coordinates defining the borders of the region. |
vec.inout |
logical. If |
... |
currently not used (kept for back compatibility). |
The function works as follows:
First it creates a grid using the R function
expand.grid and then it uses the geoR'
internal function
.geoR_inout() which wraps usage of SpatialPoints
and over
from the package sp to extract the points
of the grid which are inside the polygon.
A list with components:
xypoly |
an n x 2 matrix with the coordinates of the points inside the polygon. |
vec.inout |
logical, a vector indicating whether each point of
the rectangular grid is inside the polygon. Only returned if |
Paulo Justiniano Ribeiro Jr. paulojus@leg.ufpr.br,
Peter J. Diggle p.diggle@lancaster.ac.uk.
Further information on the package geoR can be found at:
http://www.leg.ufpr.br/geoR.
poly <- matrix(c(.2, .8, .7, .1, .2, .1, .2, .7, .7, .1), ncol=2) plot(0:1, 0:1, type="n") lines(poly) poly.in <- polygrid(seq(0,1,l=11), seq(0,1,l=11), poly, vec=TRUE) points(poly.in$xy)
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