Prepare Coordinates for LHWR — prepare_lorentz

Convert common two-dimensional coordinate representations to the n x 3 Lorentz hyperboloid matrix used by bw.lhwr() and lhwr().

Usage

prepare_lorentz_coordinates(
  embedding,
  model = c("lorentz", "poincare", "spatial"),
  tol = 1e-06,
  stop_on_fail = TRUE
)

Arguments

embedding: Numeric coordinate matrix.
model: Coordinate model of embedding.
tol: Numerical tolerance used in validation.
stop_on_fail: If TRUE, throw an error when the resulting coordinates are not valid Lorentz hyperboloid points. If FALSE, return the matrix and attach the row-wise validation result as attribute valid_hyperboloid.

Value

An n x 3 Lorentz coordinate matrix with attributes input_model and valid_hyperboloid.

Details

This is a data-preparation helper. It does not estimate an embedding. Use model = "lorentz" when the input is already on the Lorentz hyperboloid, model = "poincare" for coordinates inside the Poincare disk, and model = "spatial" for ordinary two-dimensional coordinates that should be embedded as (sqrt(1 + x^2 + y^2), x, y).

Examples

S <- matrix(c(0, 0, 1, 0), ncol = 2, byrow = TRUE)
Z_spatial <- prepare_lorentz_coordinates(S, model = "spatial")

P <- matrix(c(0, 0, 0.2, -0.1), ncol = 2, byrow = TRUE)
Z_poincare <- prepare_lorentz_coordinates(P, model = "poincare")

Z_checked <- prepare_lorentz_coordinates(Z_poincare, model = "lorentz")
all(check_hyperboloid(Z_checked))