chull

Compute Convex Hull of a Set of Points

Computes the subset of points which lie on the convex hull of the set of points specified.

Keywords
graphs
Usage
chull(x, y = NULL)
Arguments
x, y
coordinate vectors of points. This can be specified as two vectors x and y, a 2-column matrix x, a list x with two components, etc, see xy.coords.
Details

xy.coords is used to interpret the specification of the points. Infinite, missing and NaN values are not allowed.
The algorithm is that given by Eddy (1977).

Value

An integer vector giving the indices of the unique points lying on the convex hull, in clockwise order. (The first will be returned for duplicate points.)

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole. Eddy, W. F. (1977) A new convex hull algorithm for planar sets. ACM Transactions on Mathematical Software, 3, 398--403. Eddy, W. F. (1977) Algorithm 523. CONVEX, A new convex hull algorithm for planar sets[Z]. ACM Transactions on Mathematical Software, 3, 411--412.

See Also

xy.coords, polygon

Aliases
  • chull
Examples
library(grDevices) X <- matrix(stats::rnorm(2000), ncol = 2) chull(X) ## Not run: # # Example usage from graphics package # plot(X, cex = 0.5) # hpts <- chull(X) # hpts <- c(hpts, hpts[1]) # lines(X[hpts, ]) # ## End(Not run)
Documentation reproduced from package grDevices, version 3.3.1, License: Part of R 3.3.1

Community examples

Looks like there are no examples yet.