Unable to add points in rEEMSplots

[nehasavant]

Hello,

I'm using rEEMSplots to plot results, and I'd like to add the original points to the migration surface graph. I use the following syntax and do not get any errors, but the points are not appearing on my output graph.

plot_p <- rEEMSplots::eems.plots(mcmcpath = eems_results_P, plotpath = names_figures_P, add.grid = TRUE, projection.in = "+proj=longlat +datum=WGS84", projection.out = "+proj=longlat +datum=WGS84", add.outline = TRUE, longlat = FALSE, m.plot.xy = { points(coord_P, col = "purple", pch=18) }, q.plot.xy = { points(coord_P, col = "purple", pch=18) })

In addition, is it possible to overlay a streams/waterbodies shapefile on top of the migration/diversity plots?

Thank you!

[tim-oconnor]

Hi nehasavant -- late reply, but perhaps it'll help you / others. This is absolutely possible, but I've also had issues before. You can just use the "map" or "plot" commands that you want within the m.plot.xy and q.plot.xy arguments. The only trick is to ensure that you first project the points or shapefiles into the same CRS as the EEMS rasters (use spTransform from the sp / rgdal packages).

-Tim

[dipetkov]

Anything inside the m.plot.xy and m.plot.xy is added on top of the raster plot but the statements are not parsed (in order to apply projections, for example). So you have to do it by hand.

Here is the relevant example:

library("rEEMSplots")
extdata_path <- system.file("extdata", package = "rEEMSplots")
eems_results <- file.path(extdata_path, "EEMS-example")
name_figures <- file.path(path.expand("~"), "EEMS-example")

library("rgdal")
projection_none <- "+proj=longlat +datum=WGS84"
projection_mercator <- "+proj=merc +datum=WGS84"

# Start with points specified in (longitude, latitude)
coords <- matrix(c(
  -10, 10,
  10, 10,
  30, 0,
  40, -10,
  30, -20
), ncol = 2, byrow = TRUE)
colors <- c("red", "green", "blue", "purple", "orange")
labels <- LETTERS[1:5]

# Transform the coordinates into the same projection
# that will be used to transform the migration rates
coords_merc <- sp::spTransform(
  SpatialPoints(coords, CRS(projection_none)),
  CRS(projection_mercator)
)

# `coords_merc` is a SpatialPoints structure
# but we only need the coordinates themselves
coords_merc <- coords_merc@coords

# So to summarize start with points in one projection
coords
# And project them to the target projection
coords_merc

eems.plots(
  mcmcpath = eems_results,
  plotpath = paste0(name_figures, "-labels-projected"),
  longlat = TRUE,
  projection.in = projection_none,
  projection.out = projection_mercator,
  m.plot.xy = {
    text(coords_merc, col = colors, pch = labels, font = 2)
  },
  q.plot.xy = {
    text(coords_merc, col = colors, pch = labels, font = 2)
  }
)