From: Chris White <cwprogram@...>
Date: 2011-09-10T02:05:15+09:00
Subject: Re: Creating a hash from two arrays


> Hi. Can anyone help with this? I'd like to end with a hash like so:
> 
> hash = {{"A" => 'alpha'}, {'B' => 'bravo'}} etc...
> 
> 
> 
> I'm not sure whether I can use group_by and how to handle case
> insensitity. Cheers for any help.
> 
> 
> 
> irb(main):001:0> s = ('A'..'Z').to_a
> => ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
> "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"]
> 
> irb(main):003:0> t = %w(alpha bravo Charlie Zebra)
> => ["alpha", "bravo", "Charlie", "Zebra"]
I will suggest something different based on what you wish to do. This uses inject:
---t = %w(alpha bravo Charlie Zebra)
result = t.inject(Hash.new) do | words, word |  first_letter = word[0].upcase  words[first_letter] = word  wordsend---
result looks like this:
{"A"=>"alpha", "B"=>"bravo", "C"=>"Charlie", "Z"=>"Zebra"} 
Now, if there's a chance that words with start with the letter A, or any other letter might occur, I instead recommend an array based approach:
---t = %w(alpha bravo Charlie Zebra)
result = t.inject(Hash.new) do | words,word |  first_letter = word[0].upcase  if words.has_key? first_letter    words[first_letter] << word  else    words[first_letter] = [word]  end  wordsend---
result produces:
{"A"=>["alpha"], "B"=>["bravo"], "C"=>["Charlie"], "Z"=>["Zebra"]}  
In both cases, the first letter is uppercased to handle being case insensitive. Let me know if you have any questions regarding this, or if you have a different problem you are trying to solve.
Best Regards,Chris White