data <- as.data.frame(as.matrix(c("A","B","C","B","C","C","A","B"),8,1))
data
  V1
1  A
2  B
3  C
4  B
5  C
6  C
7  A
8  B
library(dummies)
data <- cbind(data, dummy(data$V1, sep = "_"))
> data
  V1 data_A data_B data_C
1  A      1      0      0
2  B      0      1      0
3  C      0      0      1
4  B      0      1      0
5  C      0      0      1
6  C      0      0      1
7  A      1      0      0
8  B      0      1      0