library(GGally)
library(dplyr)

# import
cheese <- rxImport(inData = “/media/sf_docVM/cheese.txt")
str(cheese)
summary(cheese[,-c(1,2)])

#
cheese %>%
    select(-c(.rxRowNames, Case)) %>%
    GGally::ggpairs(title = "without transformation")

#with transformation
cheese %>%
    select(-c(.rxRowNames, Case)) %>%
    mutate_all(funs(log2)) %>%
    GGally::ggpairs(title = "log2 transformation")

#Boxcox transformation
apply(cheese[,-c(1,2)], 2, function(x) caret::BoxCoxTrans(x)$lambda)
caret::BoxCoxTrans(cheese$Lactic[-3])$lambda # exclude negative value...

cheese %>%
    select(-c(.rxRowNames, Case)) %>%
    mutate(taste_boxcox = taste^.6,
           Acetic_log = log2(Acetic),
           H2S_boxcox = H2S^-.1,
           Lactic_boxcox = Lactic^.5) %>%
    select(-c(taste:Lactic)) -> cheese_trans
cheese_trans %>%
    GGally::ggpairs(title = "log2 & box-cox transformation")
rxLinMod(formula = taste_boxcox ~ H2S_boxcox, data = cheese_trans) %>% summary
rxLinMod(formula = taste_boxcox ~ H2S_boxcox+Lactic_boxcox, data = cheese_trans) %>% summary