#### This function performs A Box-Cox Transformation on a raster dataset ####

boxcox_raster <- function(bcras){

  # require the necessary packages
    require(caret)
    require(raster)
    require(vcdExtra)
  
  # first get the frequency table (attribute table) of the raster
    att_tab <- raster::freq(x = bcras, 
                            digits = 0,
                            useNA = 'no')

  # then expand this out to case form for box-cox
    bc_tab <- expand.dft(x = att_tab, 
                         var.names = NULL,
                         freq = "count")

  # then convert the bc_tab dataframe to a vector of values for box-cox
    bc_data <- as.vector(bc_tab)

  # then run BoxCoxTrans on the raster values to identify a lambda value to transform the data
    bc_res <- BoxCoxTrans(y = bc_data,
                          fudge = 0.1)

  # and export the lambda value 
    bc_lambda <- bc_res$lambda

  # then transform the original raster using this lambda value
    result <- bcras^bc_lambda

}