| inashape3d {alphashape3d} | R Documentation |
Test of the inside of an \alpha-shape
Description
This function checks whether points are inside an \alpha-shape.
Usage
inashape3d(as3d, indexAlpha = 1, points)
Arguments
as3d |
An object of class |
indexAlpha |
A single value or vector with the indexes of
|
points |
A 3-column matrix with the coordinates of the input points. |
Details
The function inashape3d checks whether each point in points is
inside the \alpha-shape for each value of \alpha in
as3d$alpha[indexAlpha].
If indexAlpha="all" or indexAlpha="ALL" then the function
checks whether each point in points is inside the \alpha-shape
for all values of \alpha in as3d$alpha.
Value
If indexAlpha is a single value then the function returns a
vector of boolean of length the number of input points. The element at
position i is TRUE if the point in points[i,] is inside
the \alpha-shape.
Otherwise inashape3d returns a list of vectors of boolean values
(each object in the list as described above).
See Also
Examples
T1 <- rtorus(2000, 0.5, 2)
T2 <- rtorus(2000, 0.5, 2, ct = c(2, 0, 0), rotx = pi/2)
x <- rbind(T1, T2)
ashape3d.obj <- ashape3d(x, alpha = 0.4)
# Random sample of points in a plane
points <- matrix(c(5*runif(10000) - 2.5, rep(0.01, 5000)), nc = 3)
in3d <- inashape3d(ashape3d.obj, points = points)
plot(ashape3d.obj, transparency = 0.2)
colors <- ifelse(in3d, "blue", "green")
points3d(points, col = colors)