Reshaping data frame with duplicates

Question

I have what should be a simple reshaping problem, but I can\'t figure it out. Part of my data looks like this:

foo <- structure(list(grade = c(3, 3, 4, 4,         


        

Answer 1

If you want to reshape and you have duplicates, you're going to need to give each pair a unique id:

foorle <- rle(foo$grade)
fooids <- rep(seq_len(length(foorle$values)), times=foorle$lengths)

fooids
 [1]  1  1  2  2  3  3  4  4  5  5  6  6  7  7  8  8  9  9 10 10

Now you'll be able to use reshape properly:

idfoo <- cbind(id=fooids, foo)

library(reshape)
dcast(idfoo, id+grade~var.type, value.var="var.val")

   id grade SE  SS
1   1     3 47 120
2   2     4 46 120
3   3     5 46 120
4   4     6 47 120
5   5     7 46 120
6   6     8 46 120
7   7     3 12 120
8   8     4 14 120
9   9     5 16 120
10 10     6 20 120

EDIT: Please note I'm assuming your data is in order, else you'll have problems distinguishing between duplicates. If it isn't, you can always use order so that it is.