scbrown86

# https://doi.org/10.1023/A:1015508322413
# The refet() function assumes that the rasters are ordered Jan-Dec
# if a different order is required, make sure a z-index is provided for
# the Tmin raster. The refet() function will then calculate
# julian dates and month lengths off this z-index.

library(raster)
library(sirad)

Tmin <- resample(crop(x = getData("worldclim", res = 10, var="tmin"),

scbrown86

ortho_plot <- function(poly, lat = 55, lon = 20, lwd = 0.25, bgc = "#bfd7ea") {
  require(sf); require(mapview)
  sf_use_s2(FALSE)
  # Define the orthographic projection
  # Choose lat_0 with -90 <= lat_0 <= 90 and lon_0 with -180 <= lon_0 <= 180
  ortho <- sprintf('+proj=ortho +lat_0=%s +lon_0=%s +x_0=0 +y_0=0 +a=6371000 +b=6371000 +units=m +no_defs', lat, lon)
  assign(x = "ortho_crs", value = ortho, envir = .GlobalEnv)
  # Define the polygon that will help you finding the "blade"
  # to split what lies within and without your projection
  # buffer is == Semimajor radius of the ellipsoid axis

scbrown86

##%######################################################%##
#                                                          #
####           Extracts probability estimates           ####
####         from calibration/validation points         ####
####          for n-dimensional hypervolumes,           ####
####               and compares these to                ####
####    background values from the same hypervolume.    ####
####         Values are then rescaled to {0, 1}         ####
####          based on 10% omission rate, with          ####
####        upper values capped at 90%. AUC and         ####

scbrown86

# Small function for correctly plotting a global map whith a rotated projection (i.e. non standard centre longitude)
## from here - https://stackoverflow.com/a/68313482
rotate_prj <- function(x, crs) {
  stopifnot(inherits(x, what = "sf"))
  stopifnot(inherits(st_crs(crs), "crs"))
  # make the data valid before doing anything else!
  x <- st_make_valid(x)
  # determine the rotated/centre longitude from crs
  lon <- sapply(strsplit(as.character(st_crs(crs)[2]), "\n"), trimws)
  lon <- lon[which(grepl(pattern = "Longitude of natural origin", x = lon))]

scbrown86

get_point_at_distance <- function(lon, lat, d, bearing, R = 6378137) {
  # lat: initial latitude, in degrees
  # lon: initial longitude, in degrees
  # d: target distance from initial point (in m)
  # bearing: (true) heading in degrees
  # R: mean radius of earth (in m)
  # Returns new lat/lon coordinate {d} m from initial, in degrees
  stopifnot("lon value not in range {-180, 180}" = !any(lon < -180 | lon > 180))
  stopifnot("lat value not in range {-90, 90}" = !any(lat < -90 | lat > 90))
  stopifnot("bearing not in range {0, 360}" = !any(bearing < 0 | bearing > 360))