Question

I would like to use R to produce a relationship matrix from a list of known relations.
For example, with the following dataset :

John Green
Mary Blue
Mary Red
John Blue

I would like to have :

       Green Blue Red
John     1     1   0
Mary     0     1   1

I didn’t found how to do this.
Thanks in advance for any suggestion.

Answer 1

You can use table.

people <- c("John", "Mary", "Mary", "John")
cols <- c("Green", "Blue", "Red", "Blue")
df <- data.frame(people, cols)

table(df)

      cols
people Blue Green Red
  John    1     1   0
  Mary    1     0   1