Rasterise a GFW effort tibble onto a target grid

Turn the long-format apparent-fishing-hours tibble returned by gfwr::gfw_ais_fishing_hours() (formerly gfwr::get_raster()) into a multi-layer SpatRaster on the package's canonical study grid. Each level of layer_by becomes its own layer, named effort_<level> (e.g. effort_drifting_longlines).

Usage

gfw_effort_to_raster(
  effort,
  grid = NULL,
  layer_by = "geartype",
  value = "Apparent Fishing Hours",
  fun = "sum"
)

Arguments

effort

Data frame. Output of gfwr::gfw_ais_fishing_hours() (a long-format tibble with at minimum Lat, Lon, a value, and a grouping column).

grid

SpatRaster. Target grid (extent, resolution, CRS) — typically the same grid used for species ranges and WOA extraction. If grid = NULL, assume target grid from input effort data frame.

layer_by

Character. Column in effort whose levels become layers. NULL produces a single-layer total-effort raster. Default "geartype".

value

Character. Column in effort to aggregate. Default "Apparent Fishing Hours".

fun

Character or function. Aggregation applied to records that fall into the same cell × layer level. Default "sum".

Value

A SpatRaster with one layer per layer_by level (or one layer if layer_by = NULL). Layer names follow effort_<level>.

Details

The input is expected to carry a cell centroid (Lat, Lon), a value column (default "Apparent Fishing Hours"), and one categorical column matching the API's group_by — for example geartype or flag (note lower-case; this is what gfwr actually returns). Records that fall into the same target cell × layer level are aggregated with fun.

Examples

if (FALSE) { # \dontrun{
jpn_eez_id <- gfwr::gfw_region_id(region = "JPN", region_source = "EEZ")$id
effort <- gfwr::gfw_ais_fishing_hours(
  spatial_resolution  = "LOW",        # 0.01 deg
  temporal_resolution = "YEARLY",      # one bucket per year in [start, end]
  start_date          = "2022-01-01",
  end_date            = "2022-12-31",
  region              = jpn_eez_id,
  region_source       = "EEZ",
  group_by            = "GEARTYPE"
)

# Returns data.frame 
head(effort)

# Create multi-layer SpatRaster from data.frame, one for each geartype
effort_by_gear <- gfw_effort_to_raster(
  effort   = effort,
  layer_by = "geartype",
  value    = "Apparent Fishing Hours",
  fun      = "sum"
)

# Plot drifitng longlines effort
terra::plot(effort_by_gear$effort_drifting_longlines)
} # }