This is a simple example of what I'm facing. I've my factor levels B-1, B-2, B-9, B-10, B-11 and want to arrange them in above given order. Here I can easily rearrange the levels, however, in my data I do have complex structure and would like to do it through some coding. I wonder how to arrange these factor levels in their logical order.
set.seed(12345)
f <- rep(c("B-1", "B-2", "B-9", "B-10", "B-11"), each=3)
Y <- runif(n=15, min=100, max=1000)
df <- data.frame(f, Y)
levels(df$f)
[1] "B-1" "B-10" "B-11" "B-2" "B-9"
library(gtools)
mixedsort(df$f)
[1] B-1 B-1 B-1 B-10 B-10 B-10 B-11 B-11 B-11 B-2 B-2 B-2 B-9 B-9 B-9
Levels: B-1 B-10 B-11 B-2 B-9
df2 <- df[mixedorder(df$f), ]
df3 <- within(df,
Position <- factor(f,
levels=names(sort(table(f),
decreasing=TRUE))))
levels(df3$Position)
[1] "B-1" "B-10" "B-11" "B-2" "B-9"
Now I can have the solution to this question which was closed immediately as I posted it. Thanks @akrun for your help.
We can specify the levels as the mixedsorted levels of the 'f' column.
df$f <- factor(df$f, levels=mixedsort(levels(df$f), decreasing=TRUE))
levels(df$f)
#[1] "B-1" "B-2" "B-9" "B-10" "B-11"
Or as suggested by @Ben Bolker, a variation would be
df <- transform(df,f=factor(f,levels=mixedsort(levels(f),
decreasing=TRUE)))
and I guess - is interpreted as minus sign as @Gregor suggested in the comments.