create_balls function

Make a cover of balls

create_balls(data, dists, eps)

Arguments

• data: A data frame.
• dists: A distance matrix for the data frame.
• eps: A positive real number.

Returns

A list of vectors of data point names, one list element per ball. The output is such that every data point is contained in a ball of radius $\varepsilon$, and no ball center is contained in more than one ball. The centers are datapoints themselves.

Examples

num_points = 5000

P.data = data.frame(
  x = sapply(1:num_points, function(x)
    sin(x) * 10) + rnorm(num_points, 0, 0.1),
  y = sapply(1:num_points, function(x)
    cos(x) ^ 2 * sin(x) * 10) + rnorm(num_points, 0, 0.1),
  z = sapply(1:num_points, function(x)
    10 * sin(x) ^ 2 * cos(x)) + rnorm(num_points, 0, 0.1)
)

P.dist = dist(P.data)
balls = create_balls(data = P.data, dists = P.dist, eps = .25)