swd_format: Prepare data in Maxents swd format.

swd_format It reshapes your occurrence and background information using the format samples with data (swd) to run maxent with an ordinary samples file.

swd_format(
  env_layers,
  nbg = NULL,
  occs_points,
  sp_name = "sp",
  longitude,
  latitude
)

Arguments

env_layers	A raster stack or brick with the environmental information.
nbg	Number of points for the background data.
occs_points	A data frame with longitude and latitude data.
sp_name	Species name. Default sp_name="sp".
longitude	Column name containing longitude data.
latitude	Column name containing latitude data.

Value

A list with the occurrence or/and background points in swd format. Note that coordinates correspond to pixel centroids

Details

The difference between the typical way of running MaxEnt models and it is that the program doesn’t need to look in the environmental layers to obtain values for the variables at the sample points or the background points. each time that you call maxent (see maxent_call). One of the main advantages is that MaxEnt runs much faster see section SWD Format here https://biodiversityinformatics.amnh.org/open_source/maxent/Maxent_tutorial2017.pdf for details.

Examples

if (FALSE) {
# Bioclimatic layers path
wcpath <- list.files(system.file("extdata/bios",
                                package = "ntbox"),
                    pattern = ".tif$",full.names = TRUE)
# Bioclimatic layers
wc <- raster::stack(wcpath)
# Occurrence data for the giant hummingbird (Patagona gigas)
pg <- utils::read.csv(system.file("extdata/p_gigas.csv",
                                  package = "ntbox"))

pg_swd <- ntbox::swd_format(env_layers=wc,
                            nbg=10000,
                            occs_points =pg,
                            sp_name="p_gigas",
                            longitude = "longitude",
                            latitude  = "latitude")

head(pg_swd$occs_swd)

head(pg_swd$bg_swd)

}