fvalues4levels changes levels of a factor to numeric variable for plotting of the PRC diagram
fvalues4levels(object, fctr)a numeric named vector (names are levels)
Design <- data.frame(week=gl(11, 12, labels=c(-4, -1, 0.1, 1, 2, 4, 8, 12, 15, 19, 24)),
dose=factor(rep(c(0.1, 0, 0, 0.9, 0, 44, 6, 0.1, 44, 0.9, 0, 6), 11)))
fvalues4levels(Design, "week")
#> -4 -1 0.1 1 2 4 8 12 15 19 24
#> -4.0 -1.0 0.1 1.0 2.0 4.0 8.0 12.0 15.0 19.0 24.0
# fvalues4levels strips the starting k characters so as to find numbers,e.g.
Design$week2 <- factor(paste("Week", Design$week))
levels(Design$week2)
#> [1] "Week -1" "Week -4" "Week 0.1" "Week 1" "Week 12" "Week 15"
#> [7] "Week 19" "Week 2" "Week 24" "Week 4" "Week 8"
fvalues4levels(Design, "week2")
#> Week -1 Week -4 Week 0.1 Week 1 Week 12 Week 15 Week 19 Week 2
#> -1.0 -4.0 0.1 1.0 12.0 15.0 19.0 2.0
#> Week 24 Week 4 Week 8
#> 24.0 4.0 8.0
# they may not be in increasing order in general,
# but will be after sorting:
sort(fvalues4levels(Design, "week2"))
#> Week -4 Week -1 Week 0.1 Week 1 Week 2 Week 4 Week 8 Week 12
#> -4.0 -1.0 0.1 1.0 2.0 4.0 8.0 12.0
#> Week 15 Week 19 Week 24
#> 15.0 19.0 24.0
# the resulting numeric variable:
numvar <- fvalues4levels(Design, "week2")[Design[,"week2"]]
summary(numvar)
#> Min. 1st Qu. Median Mean 3rd Qu. Max.
#> -4.000 0.100 4.000 7.282 15.000 24.000
length(numvar)== nrow(Design)
#> [1] TRUE