tests/testthat/test-DamerauLevenshtein.R

In comparator: Comparison Functions for Clustering and Record Linkage

# Check weights
# Check use_bytes
# Check ignore_case

context("Damerau-Levenshtein distance")

examples_equal_weights <- list(
  list(x = "abc", y = "abc", true_dist = 0),            # identical
  list(x = "plane", y = "plant", true_dist = 1),        # substitution
  list(x = "color", y = "colour", true_dist = 1),       # insertion
  list(x = "favourite", y = "favorite", true_dist = 1), # deletion
  list(x = "abc", y = "ca", true_dist = 2),             # transposition + insertion
  list(x = "abc", y = "acb", true_dist = 1),            # transposition
  list(x = "1234", y = "", true_dist = 4),              # complete deletion
  list(x = "", y = "1234", true_dist = 4),              # complete insertion
  list(x = "", y = "", true_dist = 0),                  # empty
  list(x = "positive", y = "evitisop", true_dist = 6),  # reverse
  list(x = "café", y = "cafe", true_dist = 1),          # character with diacritic
  list(x = "Saturday", y = "Sunday", true_dist = 3),
  list(x = list(c("A", "B", "B", "A")), y = list(c("A", "B", "A", "B")), true_dist = 1)
)

test_that("Damerau-Levenshtein distance is correct when weights are equal", {
  for (example in examples_equal_weights) {
    with(example, 
         expect_equal(DamerauLevenshtein()(x, y), true_dist))
    
  }
})

examples_nonequal_weights <- list(
  list(comparator = DamerauLevenshtein(insertion = 10, deletion = 10, substitution = 10), 
       x = "abc", y = "abc", true_dist = 0),               # identical
  list(comparator = DamerauLevenshtein(substitution = 0.9), 
       x = "plane", y = "plant", true_dist = 0.9),         # substitution
  list(comparator = DamerauLevenshtein(insertion = 0.9), 
       x = "color", y = "colour", true_dist = 0.9),        # insertion
  list(comparator = DamerauLevenshtein(deletion = 0.9), 
       x = "favourite", y = "favorite", true_dist = 0.9),  # deletion
  list(comparator = DamerauLevenshtein(transposition = 100), 
       x = "abc", y = "ca", true_dist = 3),                # transposition + insertion
  list(comparator = DamerauLevenshtein(insertion = 10, deletion = 20), 
       x = "", y = "", true_dist = 0),                     # empty
  list(comparator = DamerauLevenshtein(transposition = 1e-10), 
       x = "positive", y = "evitisop", true_dist = 1.3e-9) # reverse
)

test_that("Damerau-Levenshtein distance is correct when weights are not equal", {
  for (example in examples_nonequal_weights) {
    with(example, 
         expect_equal(comparator(x, y), true_dist))
    
  }
})

examples_normalized <- list(
  list(x = "abc", y = "abc", true_dist = 0),                     # identical
  list(x = "plane", y = "plant", true_dist = 2/(2*5+1)),         # substitution
  list(x = "color", y = "colour", true_dist = 2/(5+6+1)),        # insertion
  list(x = "favourite", y = "favorite", true_dist = 2/(9+8+1)),  # deletion
  list(x = "abc", y = "ca", true_dist = 2*2/(3+2+2)),            # transposition + insertion
  list(x = "abc", y = "acb", true_dist = 2*1/(2*3+1)),           # transposition
  list(x = "1234", y = "", true_dist = 2*4/(4+4)),               # complete deletion
  list(x = "", y = "1234", true_dist = 2*4/(4+4)),               # complete insertion
  list(x = "", y = "", true_dist = 0),                           # empty
  list(x = "positive", y = "evitisop", true_dist = 2*6/(2*8+6)), # reverse
  list(x = "café", y = "cafe", true_dist = 2*1/(2*4+1)),         # character with diacritic
  list(x = "Saturday", y = "Sunday", true_dist = 2*3/(8+6+3))
)

test_that("Damerau-Levenshtein distance is correct when normalized", {
  for (example in examples_normalized) {
    with(example, 
         expect_equal(DamerauLevenshtein(normalize = TRUE)(x, y), true_dist))
    
  }
})