R/pathos.R

In mdsumner/graticule: Meridional and Parallel Lines for Maps

#  Create a mesh of evenly spaced lines in another projection.
#
#  @param x object to build line mesh for
#  @param proj the other projection
#
#  @return spatial object
#  @export
#
#  @examples
#  \dontrun{
#  library(maptools)
#  data(wrld_simpl)
#  library(raster)
#  w <- subset(wrld_simpl, NAME == "Australia")
#  plot(w)
#  laea <- pathologicule(w, "+proj=laea +lon_0=147 +lat_0=-42 +ellps=WGS84")
#  stere <- pathologicule(w, "+proj=stere +lon_0=147 +lat_0=-42 +ellps=WGS84")
#  plot(laea, add = TRUE, col = "dodgerblue")
#  plot(stere, add = TRUE, col = "firebrick")
#
#  stere <- "+proj=stere +lat_0=-90 +ellps=WGS84"
#  p <- spTransform(subset(wrld_simpl, coordinates(wrld_simpl)[,2] < -20), stere)
#  plot(extent(p) + 1e6, asp = 1, type = "n"); plot(p, add = TRUE)
#  laea <- pathologicule(p, "+proj=laea +lon_0=147 +lat_0=-72 +ellps=WGS84")
#  stere <- pathologicule(p, "+proj=stere +lon_0=147 +lat_0=-42 +ellps=WGS84")
#  plot(laea, add = TRUE, col = "dodgerblue")
#  plot(stere, add = TRUE, col = "firebrick")
#  }
# gridicule <- function(x, proj) {
#   y <- spTransform(x, proj)
#   xr <- xrange(y)
#   yr <- yrange(y)
#   xs <- seq(xr[1], xr[2], length = 15)
#   ys <- seq(yr[1], yr[2], length = 15)
#   g <- graticule(xs, ys)
#   projection(g) <- proj
#   spTransform(g, projection(x))
# }