Converting R Factors into Binary Matrix Values

Question

I would like to convert my dataframe into a matrix that expands a single factor column into multiple ones and assigns a 1/0 depending on the factor. Fo

Answer 1

dat <- read.table(text =' C1 C2 C3
A  3  5
B  3  4
A  1  1',header=T)

Using transform

transform(dat,C1_A =ifelse(C1=='A',1,0),C1_B =ifelse(C1=='B',1,0))[,-1]
  C2 C3 C1_A C1_B
1  3  5    1    0
2  3  4    0    1
3  1  1    1    0

Or to get more flexbility , with within

within(dat,{ 
             C1_A =ifelse(C1=='A',1,0)
             C1_B =ifelse(C1=='B',1,0)})

  C1 C2 C3  C1_B C1_A
1  A  3  5    0    1
2  B  3  4    1    0
3  A  1  1    0    1