Question

Here is my data:

sub <- paste ("s", 1:6, sep = "")
mark1a <- c("A", "A", "B", "d1", "A", 2)
mark1b <- c("A", "B", "d1", 2, "d1", "A")
myd <- data.frame (sub, mark1a, mark1b)
myd 
     sub mark1a mark1b
1  s1      A      A
2  s2      A      B
3  s3      B     d1
4  s4     d1      2
5  s5      A     d1
6  s6      2      A

I want create a design matrix of the pair of variables (columns) – mark1a and mark1b. A design matrix will consists of length (unique (c(mark1a, mark1b))) for each unique (c(mark1a, mark1b). then 1 or 2 based on if the particular number is present once or twice in the columns and else 0. The following is expected output (not a figure):

I could understand how this can be done:

Answer 1

You could try something like this:

cbind(myd, t(apply(myd, 1, function(x) sapply(unique(unlist(myd[, 2:3])), function(y) sum(x==y)))))
1  s1      A      A 2 0  0 0
2  s2      A      B 1 1  0 0
3  s3      B     d1 0 1  1 0
4  s4     d1      2 0 0  1 1
5  s5      A     d1 1 0  1 0
6  s6      2      A 1 0  0 1