Senso <- read.table("https://husson.github.io/livre_exo/chap11_ex6.csv", header = TRUE, sep=";", encoding = "latin1")

for (i in 1:2) Senso[,i] <- as.factor(Senso[,i])

library(FactoMineR)
AovSum(Note ~ Jour + Chocolat + Chocolat:Jour, data = Senso)

AovSum(Note ~ Jour + Chocolat, data = Senso)

by(Senso[,"Note"],Senso[,"Chocolat"],mean)