txt <- c("peter likes red", "mary likes green", "bob likes blue")

voc <- c("peter", "mary", "bob", "red", "green", "blue")

c("peter red", "mary green", "bob blue")

foo <- VCorpus(VectorSource(txt))
inspect(DocumentTermMatrix(foo, list(dictionary = voc)))
Non-/sparse entries: 6/12
Sparsity           : 67%
Maximal term length: 5
Weighting          : term frequency (tf)

    Terms
Docs blue bob green mary peter red
   1    0   0     0    0     1   1
   2    0   0     1    1     0   0
   3    1   1     0    0     0   0