R/countPoints.r

In enmSdmX: Species Distribution Modeling and Ecological Niche Modeling

#' Number of points in a "spatial points" object
#'
#' Returns the number of points in a \code{sf} or \code{SpatVector} object. This is typically done using either \code{length(x)} or \code{nrow(x)}, depending on whether the object in question has rows or not. This function helps in ambiguous cases, so users need not care if \code{nrow} or \code{length} is needed.
#'
#' @param x Object of class \code{sf} or \code{SpatVector}
#' @param byFeature If \code{FALSE}, return number of points for all features combined. If \code{TRUE}, report number of points per feature.
#'
#' @return Numeric.
#'
#' @examples
#'
#' library(sf)
#'
#' # lemur occurrence data
#' data(lemurs)
#' wgs84 <- getCRS('WGS84')
#' occs <- lemurs[lemurs$species == 'Eulemur fulvus', ]
#' occs <- sf::st_as_sf(occs, coords=c('longitude', 'latitude'), crs=wgs84)
#' 
#' countPoints(occs)
#'
#' @export
countPoints <- function(x, byFeature = FALSE) {

	if (inherits(x, 'SpatVector')) {
		if (terra::geomtype(x) == 'points') out <- nrow(x)
	} else {
		# out <- mapview::npts(x, by_feature=byFeature)
		x <- sf::st_as_sf(x)
		if (byFeature) {
			out <- .countVertices(sf::st_geometry(x))
		} else {
			out <- sum(.countVertices(sf::st_geometry(x)))
		}
	}
	out
}

.countVertices <- function(x) {
	out <- if (is.list(x)) {
		sapply(sapply(x, .countVertices), sum)
	} else if (is.matrix(x)) {
		nrow(x)
	} else if (sf::st_is_empty(x)) {
		0
	} else {
		1
	}
	names(out) <- NULL
	out
}