Nearest neighbour interpolation, by Voronoi tessellation

Give every cell the value of the closest input point.

Usage

grid_voronoi(x, value = NULL, grid = NULL, duplicates = mean, ...)

Arguments

x: coordinates, or coordinates carrying their value as z; see xyz_input()
value: one value per coordinate, or NULL to use the z of x
grid: a grid_spec() to interpolate onto, or NULL for a default one
duplicates: function used to combine values at repeated coordinates, or NULL to leave them alone
...: ignored

Value

A guerrilla_grid with values.

Details

The tessellation is the picture of that rule. A Voronoi tile is exactly the region closer to its own point than to any other, so assigning each cell to the tile it falls in is nearest neighbour, drawn rather than computed.

Unlike grid_barycentric(), this fills the whole grid. Voronoi tiles cover the plane, so there is no convex hull to fall outside of – which is convenient and is also the method's main way of lying to you, since a cell far beyond the data gets a confident answer from one distant point.

Examples

xy <- cbind(runif(30), runif(30))
plot(grid_voronoi(xy, xy[, 1]))
points(xy, pch = 16, cex = 0.5)