gridRecords_mult

# DEPRECATED; since fuzzySim v3.8, the original 'gridRecords' implements 'species' argument

# wrapper for 'fuzzySim::gridRecords' for multiple species at a time
# this function takes a raster stack and a set of spatial coordinates of some species' presence records,
# and returns a data frame with the presences and absences, as well as the corresponding values of the rasters
# in the grid of pixels (cells). All pixels without any presence point for each species are returned as absences.

gridRecords_mult <- function (rst, sp.data, sp.col, coord.cols, na.rm = TRUE) 
{
  # get a list of the presence coordinates for each species:
  species <- as.character(unique(sp.data[ , sp.col]))
  pres_coords_list <- lapply(species, function(x) sp.data[sp.data[ , sp.col] == x , coord.cols])

  # grid records for each element of this list:
  gridded_records_list <- lapply(pres_coords_list, function(x) fuzzySim::gridRecords(rst = rst, pres.coords = x))
  
  names(gridded_records_list) <- species

  # replace "presence" with the corresponding species in column names:
  for (g in 1:length(gridded_records_list)) {
    names(gridded_records_list[[g]])[1] <- as.character(species[g])
  }

  # separate extracted raster values from species presences:
  extracted_vals <- gridded_records_list[[1]][ , -1]
  
  for(spc in species) {
    extracted_vals <- merge(gridded_records_list[[spc]][ , c(spc, "cells")], extracted_vals, by = "cells")
  }

  return(extracted_vals)
}