R: Plot: Re-arranging the order of variables

Question

I want to create a barplot in R. However, I would like to re-arrange the variables on the x-axis, not by frequency but by \'meaning\'.

Imagine I have the following

Answer 1

We can use factor with levels specified

plot(factor(df$Radio, levels=c("C", "E", "B", "A", "D", "F")))