assets/make_plot_grid.md

In afsc-gap-products/akgfmaps: Alaska Groundfish and Ecosystem Survey Area Mapping

Return coordinates for plotting gridded data using make_2d_grid()

Feature added in 3.3.0 (see NEWS)

This example show how to use the make_2d_grid() function to produce grid cell centroid coordinates that facilitate plotting data from 2d grids that are used for spatial analyses (e.g. using VAST or sdmTMB). Otherwise this would require post-processing manipulation of gridded data.

The plotting coordinate columns (lon_plot and lat_plot) should only be used for visualization.

library(akgfmaps)

# Bounding box used for the EBS
vast_bbox <- c(xmin = -2846314.206900,
              ymin = 251495.775400,
              xmax = 2128157.793100,
              ymax = 2859111.775400)

# Grid cell resolution in meters (equivalent to 2 nautical miles)
res <- c(3704, 3704)

ebs_layers <- akgfmaps::get_base_layers(select.region = "sebs",
                                        set.crs = "EPSG:3338")

ebs_grid <- akgfmaps:::make_2d_grid(obj = ebs_layers$survey.strata,
                                    resolution = res,
                                    bbox = vast_bbox,
                                    output_type = "point",
                                    include_tile_center = TRUE)

p1 <- ggplot() +
      geom_tile(data = ebs_grid,
                mapping = aes(x = lon_plot,
                              y = lat_plot,
                              fill = Stratum))

p1

afsc-gap-products/akgfmaps documentation built on April 14, 2025, 7:13 p.m.