preprocessDataset = function()
{   
    #set.seed(SEED)
    
    xls.file = "default of credit card clients.xls"
    
    wk = loadWorkbook(paste0(orig.dir, "/", xls.file))
    dataset = readWorksheet(wk, sheet="Data", startRow=2, startCol=2,
                            check.names=FALSE)
    
    dataset = dataset %>% 
              mutate(LIMIT_BAL=as.integer(LIMIT_BAL),
                     SEX=factor(SEX),
                     EDUCATION=factor(EDUCATION), # can't order due to
                                                  # inconsistency with
                                                 # UCI description
                     MARRIAGE=factor(MARRIAGE),
                     AGE=as.integer(AGE),
                     PAY_0=as.integer(replace(PAY_0, PAY_0<0, 0)),
                     PAY_2=as.integer(replace(PAY_2, PAY_2<0, 0)),
                     PAY_3=as.integer(replace(PAY_3, PAY_3<0, 0)),
                     PAY_4=as.integer(replace(PAY_4, PAY_4<0, 0)),
                     PAY_5=as.integer(replace(PAY_5, PAY_5<0, 0)),
                     PAY_6=as.integer(replace(PAY_6, PAY_6<0, 0)),
                     BILL_AMT1=as.integer(BILL_AMT1),
                     BILL_AMT2=as.integer(BILL_AMT2),
                     BILL_AMT3=as.integer(BILL_AMT3),
                     BILL_AMT4=as.integer(BILL_AMT4),
                     BILL_AMT5=as.integer(BILL_AMT5),
                     BILL_AMT6=as.integer(BILL_AMT6),
                     PAY_AMT1=as.integer(PAY_AMT1),
                     PAY_AMT2=as.integer(PAY_AMT2),
                     PAY_AMT3=as.integer(PAY_AMT3),
                     PAY_AMT4=as.integer(PAY_AMT4),
                     PAY_AMT5=as.integer(PAY_AMT5),
                     PAY_AMT6=as.integer(PAY_AMT6),
                     `default payment next month`=factor(
                        `default payment next month`)
              )
    
    #dataset.1 = dataset %>% filter(`default payment next month` == 1)
    #dataset.0 = dataset %>% filter(`default payment next month` == 0) %>% 
    #            sample_n(nrow(dataset.1))
    #
    #dataset = rbind(dataset.0, dataset.1)

    return(dataset)
}