Efficient ways of creating matrix based on vector matches

问题

Please, consider the following code:

x <- c('dog', 'cow', 'horse', 'rabbit', 'bear', 'seal', 'lion', 'ostrich','cat', 'hamster')
y <- c('beaver', 'crow', 'donkey', 'lion', 'bear', 'fox', 'moose', 'mole')


mtx <- matrix(
  data = apply(
    X = expand.grid(
      'x' = x,
      'y' = y
    ),
    MARGIN = 1,
    FUN = function(df) {
      identical(df[['x']], df[['y']])
    }
  ),
  nrow = length(x)
)

Result
      [,1]  [,2]  [,3]  [,4]  [,5]  [,6]  [,7]  [,8]
 [1,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [2,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [3,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [4,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [5,] FALSE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE
 [6,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [7,] FALSE FALSE FALSE  TRUE FALSE FALSE FALSE FALSE
 [8,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
 [9,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[10,] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

As you can see, I'm constructing a boolean matrix based on if there's a match between the elements in vector x and y. My real life vectors are of length 4000 and 30000, so I need something that is far more efficient. Thank you!

来源：https://stackoverflow.com/questions/64104342/efficient-ways-of-creating-matrix-based-on-vector-matches