R/tin.R

In ropensci/lawn: Client for 'Turfjs' for 'Geospatial' Analysis

#' Create a Triangulated Irregular Network
#'
#' Takes a set of [data-Point]'s and the name of a z-value property
#' and creates a Triangulated Irregular Network (TIN).
#'
#' @export
#' @param pt Input points.
#' @param propertyName (character) Name of the property from which to pull z
#' values. This is optional: if not given, then there will be no extra data
#' added to the derived triangles
#' @template lint
#' @family interpolation
#' @return TIN output, as a [data-FeatureCollection].
#' @details Data returned as a collection of Polygons. These are often used for
#' developing elevation contour maps or stepped heat visualizations.
#'
#' This triangulates the points, as well as adds properties called a, b, and c
#' representing the value of the given propertyName at each of the points that
#' represent the corners of the triangle.
#' @examples
#' pts <- lawn_random(bbox = c(-70, 40, -60, 60))
#' lawn_tin(pts)
#' @examples \dontrun{
#' lawn_tin(pts) %>% view
#' lawn_tin(lawn_random(bbox = c(-70, 40, -60, 10))) %>% view
#' }
lawn_tin <- function(pt, propertyName = NULL, lint = FALSE) {
  pt <- convert(pt)
  lawnlint(pt, lint)
  assert(propertyName, 'character')
  ct$eval(sprintf("var tin = turf.tin(%s, '%s');", pt, convert(propertyName)))
  as.fc(ct$get("tin"))
}