R/defintions.r

In paul-vdb/DFO-master-sample: Western Canada Marine Master Sample

#' Build a new Master Sample with a random rotation and seed.
#'
#' Randomly generate a seed from 10,000 possible values in right now 2 dimensions.
#' Note that in van Dam-Bates et al. (2018) we required that the random seed falls into main object shape, such
#' as one of the islands in New Zealand, or within marine environment for BC west coast. However, with a random rotation, 
#' we are able to ignore that detail. If this function is used without a random rotation, we recommend running it until
#' the first master sample point does indeed fall within the largest scale of the master sample use.
#'
#'
#' @param shp Spatial feature that defines the boundary of the area to define a bounding box over.
#' @param d Dimension of the new Master Sample, at this stage we only work with d=2.
#' @param showOutput Print the rotation and random seed when it is generated.
#' @param rotate Boolean of whether or not to randomly rotate the bounding box.
#'
#' @return bounding box for a master sample.
#'
#' @examples
#' \dontrun{
#' data(NS_bioregion)
#' bb <- buildMS(shp = NS_bioregion)         # Vertically aligned master sample bounding box.
#' bb.rot <- rotate.shp(bb, bb, back = TRUE) # Actual bounding box.
#' plot(st_geometry(NS_bioregion))
#' plot(st_geometry(bb.rot), add = TRUE)
#' }
#' @export
buildMS <- function(shp, d = 2, showOutput = TRUE, rotate = TRUE)
{
  
  seed <- floor(runif(d, 0, 10000))
  # We always use base 2,3
  base <- c(2,3,5)[1:d]

  if(rotate) {
	theta <- runif(1, -pi, pi)
  }else{
	theta = 0
  }

  # Just work with sf:
  if (class(shp)[1] != "sf") 
  {
    shp <-  st_as_sf(shp)
  }
  
  # Create a Random Rotation:
  build.bb <- rotate.bb(shp, theta = theta)
  st_crs(build.bb) <- st_crs(shp)
  attr(build.bb, "seed") <- seed
  
  if(showOutput){
	cat("Seed:", seed, "\n")
	cat("Rotation:", theta, "Radians\n")
  }
  return(build.bb)
}

#' @name getProj
#' @title Define spatial objects in projection of the master sample.
#' @description Default projection of the master sample. Needed for consistency for the entire bounding box.
#' @export
getProj <- function()
{	#BC Albers
    #http://spatialreference.org/ref/epsg/3005/
    msproj <- "+proj=aea +lat_1=50 +lat_2=58.5 +lat_0=45 +lon_0=-126 +x_0=1000000 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs"
	return(msproj)
}


#' @name getBB
#' @title Get the bounding box for other functions.
#' @description Bounding box under NAD83/BC Albers.
#' @export
getBB <- function()
{
  bb.df <- c("xmin" = 85148, "ymin" = 33745, "xmax" = 1280999, "ymax" = 1351981)
  bb <- st_as_sfc(st_bbox(bb.df))

  attr(bb, "rotation") = 0
  attr(bb, "centroid") = st_centroid(bb)  
  
  st_crs(bb) <- st_crs(getProj())
  return(bb)
}

#' @name getSeed
#' @title Random seed definition for Western Canada Marine Master Sample.
#' @description Defines the random seed specific to the Western Canada Marine Master Sample. 
#' @export
getSeed <- function()
{
  seed <- c(37916, 85846)
  return(seed)
}

#' @name getRotation
#' @title Returns the radians of rotation of the bounding box.
#' @description Defines the random rotation specific to the Western Canada Marine Master Sample. 
#' @export
getRotation <- function()
{
  return(0)
}