rdataframereplacedummy-variable

Dummy variables questions : how to create a dummy-variable dataset that has repeated IDs?

I have this df

df = data.frame(ID = rep(1:3,each=5),
                group = c('A','B','A','A','C','B','D','C','B','A','A','B','B','A','C') )

and I wish to create dummy variables columns A,B,C and D with the result that if there is the value A, we make the value 1 eventhough there are many values A for the ID number 1.

The desired output is as follows

  ID A B C D
1  1 1 1 1 0
2  2 1 1 1 1
3  3 1 1 1 0
Solution 
  • +(as.data.frame.matrix(table(df)) > 0)

#  A B C D
#1 1 1 1 0
#2 1 1 1 1
#3 1 1 1 0

    Or with pivot_wider:

    tidyr::pivot_wider(df, names_from = "group", values_from = "group", 
                   values_fn = ~ +(length(.x) > 0), values_fill = 0)