One way is to use model.matrix():
model.matrix(~Species, iris)
(Intercept) Speciesversicolor Speciesvirginica
1 1 0 0
2 1 0 0
3 1 0 0
....
148 1 0 1
149 1 0 1
150 1 0 1
attr(,"assign")
[1] 0 1 1
attr(,"contrasts")
attr(,"contrasts")$Species
[1] "contr.treatment"
