How to convert two factors to adjacency matrix in R?

Question

I have a data frame with two columns (key and value) where each column is a factor:

df = data.frame(gl(3,4,labels=c(\'a\',\'b\',\'c\')), gl(6,2))
colnames(df) =          


        

Answer 1

An easy way to do it in base R:

res <-table(df)
res[res>0] <-1
res
   value
#key 1 2 3 4 5 6
#  a 1 1 0 0 0 0
#  b 0 0 1 1 0 0
#  c 0 0 0 0 1 1