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# File 'lib/string_metric/levenshtein/recursive.rb', line 6
def self.distance(from, to, options = {})
max_distance = options[:max_distance]
insertion_cost = options.fetch(:insertion_cost, 1)
deletion_cost = options.fetch(:deletion_cost, 1)
substitution_cost = options.fetch(:substitution_cost, 1)
if max_distance && (from.size - to.size).abs >= max_distance
return max_distance
end
return 0 if from == to
return to.size if from.size.zero?
return from.size if to.size.zero?
if from.chars.to_a.last == to.chars.to_a.last
cost = 0
else
cost = substitution_cost
end
if max_distance
return [distance(from.chop, to, options) + deletion_cost,
distance(from, to.chop, options) + insertion_cost,
distance(from.chop, to.chop, options) + cost,
max_distance
].min
else
return [distance(from.chop, to, options) + deletion_cost,
distance(from, to.chop, options) + insertion_cost,
distance(from.chop, to.chop, options) + cost
].min
end
end
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