R/distFct.R

In TDA: Statistical Tools for Topological Data Analysis

distFct <-
function(X, Grid) {

  if (!is.numeric(X) && !is.data.frame(X)) {
    stop("X should be a matrix of coordinates")
  }
  if (!is.numeric(Grid) && !is.data.frame(Grid)) {
    stop("Grid should be a matrix of coordinates")
  }
  if (NCOL(X) != NCOL(Grid)) {
    stop("dimension of X does not match with dimension of Grid")
  }
    
  X <- as.matrix(X) 
  Grid <- as.matrix(Grid)
  distances <- FNN::knnx.dist(X, Grid, k = 1, algorithm = c("kd_tree")) 
  dOut <- as.vector(distances)
  return(dOut)
}