Question

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Ruby Hash with Duplicate Keys?

I defined a hash:

sorted_words = Hash.new(0)
words.each { |word| sorted_words[word]=word.downcase.chars.sort{ |a, b| a.casecmp(b) }.join

Hash does not allow the duplicate keys so if I have keys like cream, scream, scream, it only considers the first two. But I want to also have the third key saved in my Hash with its appropriate value.

This is for an anagram. After the above code I create another hash and, depending on my values from the code, I create multiple arrays with each array having the anagram string.

What could be a solution for such a situation?

Answer 1

Based on the comment you’re looking for an anagram maker, here’s the basis for such a beast:

require 'pp'
require 'set'

words = %w[cream scream scream creams]

hash = Hash.new{ |h,k| h[k] = Set.new }

words.each do |w|
  hash[w.downcase.split('').sort] << w.downcase
end

pp hash

=> {["a", "c", "e", "m", "r"]=>#<Set: {"cream"}>,
 ["a", "c", "e", "m", "r", "s"]=>#<Set: {"scream", "creams"}>}

Given a set of words, this will create a hash, where each key is the sorted list of the letters in the word. The value associated with that key is a set of words with the same letters.

Because the value is a set, only unique words are stored.

Once that hash is populated, you’ll have a dictionary you can use to quickly look up other words. Take a word, break it down the same way the keys are broken down, and use that as the key in a look-up:

puts hash['creams'.downcase.split('').sort].to_a.join(', ')

outputs:

scream, creams

---

If duplicate (and redundant) words are needed:

require 'pp'
require 'set'

words = %w[cream creams scream scream]

hash = Hash.new{ |h,k| h[k] = [] }

words.each do |w|
  hash[w.downcase.split('').sort] << w.downcase
end

pp hash

=> {["a", "c", "e", "m", "r"]=>["cream"],
 ["a", "c", "e", "m", "r", "s"]=>["creams", "scream", "scream"]}

puts hash['creams'.downcase.split('').sort].to_a.sort.join(', ')

=> creams, scream, scream