Question

I have sample vector like this:

v <- c(1, 2, 1, 3, 2, 3, 3, 4, 1, 4)

What I’d like to get is frequency table which will tell me frequencies of numbers followed by another numbers .

Output:

  1 2 3 4
1 0 1 0 1
2 1 0 1 0
3 1 1 1 0
4 1 0 1 0

And then the same values in percentages.

Answer 1

If I’m thinking what you are meaning is correct, try:

xtabs(~v[-1]+v[1:(length(v)-1)])
     v[1:(length(v) - 1)]
v[-1] 1 2 3 4
    1 0 1 0 1
    2 1 0 1 0
    3 1 1 1 0
    4 1 0 1 0

This doesn’t match with your expected output, but I’m not sure how you arrived at that.

For percentages, use prop.table:

prop.table(xtabs(~v[-1]+v[1:(length(v)-1)]))*100
     v[1:(length(v) - 1)]
v[-1]        1        2        3        4
    1  0.00000 11.11111  0.00000 11.11111
    2 11.11111  0.00000 11.11111  0.00000
    3 11.11111 11.11111 11.11111  0.00000
    4 11.11111  0.00000 11.11111  0.00000