validate_bbox()

[rellimylime]

#' Validate a bounding box vector
#'
#' Checks that a bounding box is a length-4 numeric vector with valid
#' coordinate values and logical ordering. Called before any COG read
#' is attempted.
#'
#' @param bbox numeric vector. Expected format: \code{c(xmin, ymin, xmax, ymax)}
#' in EPSG:4326. Two-point format \code{c(x1, y1, x2, y2)} is not supported —
#' ensure \code{xmin < xmax} and \code{ymin < ymax} before passing.
#'
#' @return Invisibly returns \code{bbox} if valid. Stops with an informative
#' error if not.
#'
#' @details Checks performed:
#' \itemize{
#' \item Must be numeric
#' \item Must be length 4
#' \item \code{xmin} must be less than \code{xmax}
#' \item \code{ymin} must be less than \code{ymax}
#' \item Longitude values must be between -180 and 180
#' \item Latitude values must be between -90 and 90
#' \item If \code{xmin >= xmax} or \code{ymin >= ymax}, stops with a message
#' suggesting the user may have passed two points in the wrong order
#' }
#'
#' @Keywords internal
#' @Seealso Used by: \code{get_tif()}
validate_bbox <- function(bbox) {}

[FlukeAndFeather]

validate_bbox() is an example of a predicate function, meaning it's a test to see if something is true or false. By convention, predicate functions take the form is_*() (where * is the thing being tested) and they return TRUE or FALSE. For example, dplyr::is_grouped_df() checks if a data frame is grouped. The naming convention makes them read like plain language, and the return value makes it easy to use in if/else statements.

[rellimylime]

https://stackoverflow.com/questions/68711678/good-coding-practices-with-r-message-cat-print-warning-error#:~:text=Messages%20can%20be%20suppressed%20by,of%20those%20functions%20is%20implemented.

[IIDonaji]

firex/R/is_valid_bbox.R

Lines 1 to 51 in 6ab2c66

	#' Check if a bounding box is valid
	#'
	#' Tests whether a bounding box vector meets all validation criteria.
	#' This is an internal helper function used by \code{get_tif()}.
	#'
	#' @param bbox numeric vector. Expected format: \code{c(xmin, ymin, xmax, ymax)}
	#' in EPSG:4326.
	#'
	#' @return Logical. \code{TRUE} if the bounding box is valid, \code{FALSE} otherwise.
	#'
	#' @details Validation checks:
	#' \itemize{
	#' \item Must be numeric
	#' \item Must be length 4
	#' \item \code{xmin} must be less than \code{xmax}
	#' \item \code{ymin} must be less than \code{ymax}
	#' \item Longitude values must be between -180 and 180
	#' \item Latitude values must be between -90 and 90
	#' }
	#'
	#' @keywords internal
	#' @seealso Used by: \code{get_tif()}
	#'
	#' @examples
	#' \dontrun{
	#' is_valid_bbox(c(-120, 30, -100, 50)) # TRUE
	#' is_valid_bbox(c(-100, 30, -120, 50)) # FALSE - xmin > xmax
	#' }
	is_valid_bbox <- function(bbox) {
	# Check if numeric
	if (!is.numeric(bbox)) return(FALSE)
	# Check if length 4
	if (length(bbox) != 4) return(FALSE)
	xmin <- bbox[1]
	ymin <- bbox[2]
	xmax <- bbox[3]
	ymax <- bbox[4]
	# Check coordinate ordering
	if (xmin >= xmax || ymin >= ymax) return(FALSE)
	# Check longitude range (-180 to 180)
	if (xmin < -180 || xmax > 180) return(FALSE)
	# Check latitude range (-90 to 90)
	if (ymin < -90 || ymax > 90) return(FALSE)
	return(TRUE)
	}

Example output

source("R/is_valid_bbox.R")
is_valid_bbox(c(-100, 30, -120,50))
[1] FALSE
is_valid_bbox(c(-120, 30, -100,50))
[1] TRUE

[hylaea-miller]

is_valid_bbox with warnings when the output is false:

is_valid_bbox <- function(bbox) {
  if (!is.numeric(bbox) || length(bbox) != 4L) {
    warning("`bbox` must be a length-4 numeric vector: c(xmin, ymin, xmax, ymax)", call. = FALSE)
    return(FALSE)
  }
  if (bbox[1] >= bbox[3]) {
    warning("`bbox` xmin must be less than xmax: c(xmin, ymin, xmax, ymax)", call. = FALSE)
    return(FALSE)
  }
  if (bbox[2] >= bbox[4]) {
    warning("`bbox` ymin must be less than ymax: c(xmin, ymin, xmax, ymax)", call. = FALSE)
    return(FALSE)
  }
  if (bbox[1] < -180 || bbox[3] > 180) {
    warning("`bbox` longitude (x) values must be between -180 and 180", call. = FALSE)
    return(FALSE)
  }
  if (bbox[2] < -90 || bbox[4] > 90) {
    warning("`bbox` latitude (y) values must be between -90 and 90", call. = FALSE)
    return(FALSE)
  }
  return(TRUE)
}

[FlukeAndFeather]

Looking good! A few suggestions:

1. Consider restricting valid bboxes to the domain of the WRI rasters
2. Keep returning TRUE/FALSE, but attach an attribute containing the issue if it's false more info here