Array of values to matrix of pairwise evaluations in R

Question

I am trying to convert an array to a matrix where the matrix cell values evaluate if each pairwise values are the same or different.

For example: I am looking to convert an array like this:

df = data.frame(m1=c("Apple", "1", "2"), m2=c("Apple", "3", "4"), m3=c("Plum", "5", "6")) 
array = df[1,] 

to a matrix like this:

    m1  m2  m3
m1   T
m2   T   T
m3   F   F   T

Where "T" denotes that the two values are equal (i.e. first entry and the second are both equal to "apple") and "F" identifies that they are different.

Thank you!

Answer 1

You can using apply here with upper.tri

m=apply(array,2,function(x) x==array)
m[upper.tri(m)] <- ''
m
     m1      m2      m3    
[1,] "TRUE"  ""      ""    
[2,] "TRUE"  "TRUE"  ""    
[3,] "FALSE" "FALSE" "TRUE"