Simple function for fuzzy string match

simple_fuzzy_match.rb

require 'active_support/all' # mb_chars

def simple_fuzzy_match(s1, s2)
  levenshtein_distance( normalize_str(s1), normalize_str(s2) ) < 2
end

def normalize_str(s)
  s.
    mb_chars. # convert to multibyte string (ActiveSupport::Multibyte::Chars) - required in Ruby version below 2.4
    downcase. # lower case for all characters
    strip. # remove whitespace from start and end
    split(/\s+/). # RegEx split by spaces into array of words
    sort. # sort array of words alphabetically
    join(' ') # join back to string by concatenating with space for further comparison by Levenshtein distance
end

### Helper function

# http://stackoverflow.com/questions/16323571/measure-the-distance-between-two-strings-with-ruby
def levenshtein_distance(s, t)
  m = s.length
  n = t.length
  return m if n == 0
  return n if m == 0
  d = Array.new(m+1) {Array.new(n+1)}

  (0..m).each {|i| d[i][0] = i}
  (0..n).each {|j| d[0][j] = j}
  (1..n).each do |j|
    (1..m).each do |i|
      d[i][j] = if s[i-1] == t[j-1]  # adjust index into string
                  d[i-1][j-1]       # no operation required
                else
                  [ d[i-1][j]+1,    # deletion
                    d[i][j-1]+1,    # insertion
                    d[i-1][j-1]+1,  # substitution
                  ].min
                end
    end
  end
  d[m][n]
end