I am writing a package in R studio. I created function which will create object of a class "mytrack", then defined few methods from existing generics and one new method with new generic like in the below code. The new object created with this constructor will be of a class "mytrack" and will hold some metadata as well as coordinates of points which all together consist a line. Function "distance2" will calculate length of this line based on coordinates. My whole package works as well as function for calculation of distance. Problem is that I get 1 note when I do check(). Note is below after the code. My questions are the following:
- What is wrong?
- How do I fix it?
#' Constructor for object of a type "mytrack"
#'
#' @param name Name of the track
#' @param time Timestamps for points
#' @param crs CRS code
#' @param coordinates LON-LAT coordinates
#'
#' @return Object of a class "mytrack
#' @export
#'
#' @examples
#' \dontrun{
#' obj1 <- storetracks3("Track1", my_timestamps, 4326, my_coordinates)
#' }
storetracks3 <- function(name,time,crs,coordinates) {
value <- list(my_name = name, my_time = time, my_crs = crs, my_coords=coordinates)
attr(value, "class") <- "mytrack"
value
}
#' Print method for class "mytrack"
#'
#' @param x object of a class "mytrack"
#' @param ... further arguments passed to or from other methods.
#'
#' @return Prints elements of object of a class "mytrack"
#' @export
#'
#' @examples
#' \dontrun{
#' print(obj1)}
print.mytrack <- function(x, ...) {
cat("Name of this object is",x$my_name, "\n")
cat("Timestamps are ", x$my_time, "\n")
cat("CRS used is ", x$my_crs, "\n")
print(x$my_coords)
}
#' Summary method for class "mytrack"
#'
#' @param object object of a class "mytrack"
#' @param ... further arguments passed to or from other methods.
#'
#' @return Prints summary of objects of a class "mytrack"
#' @export
#'
#' @examples
#' \dontrun{
#' summary(obj1)}
summary.mytrack <- function(object, ...) {
cat("Object has ", nrow(object$my_coords), " coordinates." )
}
#' Plot method for class "mytrack"
#'
#' @param x Object of a class "mytrack"
#' @param y Not used
#' @param ... Not used
#'
#' @return Plot in Cartesian xy system where Longitude is plotted on x and
#' latitude is plotted on y
#' @export
#'
#' @examples
#' \dontrun{
#' plot(obj1)}
plot.mytrack <- function(x,y, ...) {
plot(x$my_coords,type="l")
}
#' Generic distance function
#'
#' @param obj Object of class "mytrack"
#' @param status TRUE for using S2 for distance calculation, or FALSE for not using it
#'
#' @return Distance in meters
#' @export
#'
distance2 <- function(obj,status) {
UseMethod("distance2")
}
#' Distance method for "mytrack" class objects
#'
#' @param obj Object of class "mytrack"
#' @param status TRUE for using S2 for distance calculation, or FALSE for not using it
#'
#' @return Distance in meters
#'
#' @export
#' @import sf
#' @examples
#' \dontrun{
#' distance2.mytrack(obj1,TRUE)
#' }
distance2.mytrack <- function(obj,status) {
sf::sf_use_s2(status)
points <- list()
for(row in 1:nrow(obj$my_coords)) {
point <- sf::st_point(c(obj$my_coords[c(row),c(1)],obj$my_coords[c(row),c(2)]))
points[[row]] <- point
}
sfc_object <- sf::st_sfc(points, crs=obj$my_crs)
sf_object <- sf::st_sf(geom=sfc_object)
points.nested <- sf_object %>% tidyr::nest(data=geom)
to_line <- function(tr) sf::st_cast(sf::st_combine(tr), "LINESTRING") %>% .[[1]]
(tracks <- points.nested %>% dplyr::pull(data) %>% purrr::map(to_line) %>% sf::st_sfc(crs = obj$my_crs))
return(as.integer(sf::st_length(tracks)))
}
Note I get:
distance2.mytrack: no visible binding for global variable ‘geom’
distance2.mytrack : to_line: no visible binding for global variable ‘.’
distance2.mytrack: no visible binding for global variable ‘data’
Undefined global functions or variables:
. data geom
Consider adding
importFrom("utils", "data")
to your NAMESPACE file.
Appreciate your help. I can provide more information if necessary.
