LBGtype: Create probability grid matching desired latitudinal...
In LewisAJones/LBGSim: Latitudinal biodiversity gradient simulator

Generates a modern-, bimodal, or flat-type latitudinal biodiversity gradient. Flat-type also includes a 'null model', with a completely flat gradient.

1	LBGtype(degree, res, type, restrict = FALSE, write = FALSE)

`degree`	Integer. Steepness (values = 1:5) of latitudinal biodiveristy gradient with 1 representing the shallowest gradient and 5 the steepest. If flat-type is selected in 'type', steepness can be set to 'NULL' for a null gradient.
`res`	Numeric. Resolution of the raster output. This should match the desired resolution of the study. Higher resolution raster allows the generation of more accurate species distributions but also increases computation time.
`type`	Character. Define type of latitudinal biodiversity gradient desired (options: "modern", "flat", "bimodal")
`restrict`	Logical. define whether you wish the probability gradient to be restricted. This prevents the generation of occurrences in low probability cells. Defaults to FALSE.
`write`	Logical. If TRUE, function writes ascii grid of probability gradient and png to working directory. Defaults to FALSE.