quadtree (version 0.1.14)

set_values: Change values of Quadtree cells

Description

Given a Quadtree, a set of points, and a vector of new values, changes the value of the quadtree cells containing the points to the corresponding value.

Usage

# S4 method for Quadtree,ANY,numeric
set_values(x, y, z)

Value

no return value

Arguments

x

A Quadtree

y

A two-column matrix representing point coordinates. First column contains the x-coordinates, second column contains the y-coordinates.

z

A numeric vector the same length as the number of rows of y. The values of the cells containing y will be changed to the corresponding value in z.

Details

Note that it is entirely possible for y to contain multiple points that all fall within the same cell. The values are changed in the order given, so the cell will take on the last value given for that cell.

It's important to note that this modifies the original quadtree. If you wish to maintain a version of the original quadtree, use copy beforehand to make a copy of the quadtree.

See Also

transform_values() can be used to transform the existing values of all cells using a function.

Examples

library(quadtree)
habitat <- terra::rast(system.file("extdata", "habitat.tif", package="quadtree"))

# create a quadtree
qt <- quadtree(habitat, split_threshold = .1)

# generate some random points, then change the values at those points
ext <- extent(qt)
pts <- cbind(runif(100, ext[1], ext[2]), runif(100, ext[3], ext[4]))
set_values(qt, pts, rep(10, 100))

# plot it out to see what happened
old_par <- par(mfrow = c(1, 2))
plot(qt, main = "original")
plot(qt, main = "after modification")
par(old_par)