Convert a vector into logical matrix

Question

Is there a native R function that will take an input vector and return the corresponding binary matrix where the matrix has the same number of columns as unique values in the in

Answer 1

Actually, contrasts is what you want.

contrasts(as.factor(1:3), contrasts=FALSE)

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