R/b_spline_basis.R

In smnet: Smoothing for Stream Network Data

#' @importFrom splines splineDesign

# Construct sparse B-spline basis
b_spline_basis  	<-	function(x, nseg = 10, deg = 3, range.variables){
  x_min       <- min(range.variables)
  x_max       <- max(range.variables)
  interval    <- (x_max - x_min) /nseg
  knot_seq    <- seq(x_min - deg * interval, x_max + deg * interval, by = interval)
  sparseBasis <- splineDesign(knots = knot_seq, x = x, ord = deg + 1, outer.ok = T, sparse = T)
  make_spam(sparseBasis)
}