Replicate each row of data.frame and specify the number of replications for each row?

Question

df <- data.frame(var1=c('a', 'b', 'c'), var2=c('d', 'e', 'f'), freq=1:3)What is the simplest way to expand the first two columns of the data.frame above, so thateach row appears the number of times specified in the column 'freq'?In other words, go from this: df var1 var2 freq 1 a d 1 2 b e 2 3 c f 3To this: df.expanded var1 var2 1 a d 2 b e 3 b e 4 c f 5 c f 6 c f

Answer 1

Cool question!

You can use `lapply' to apply the `rep()' function to each row, using the df$freq column to specify an argument for the `rep()' function:

Try this:

df.expanded <- as.data.frame(lapply(df, rep, df$freq))