From: Alex Gutteridge <alexg@...>
Date: 2011-02-07T21:43:55+09:00
Subject: Re: making hash key from arrays

 On Mon, 7 Feb 2011 21:28:21 +0900, Robert Klemme wrote:
> On Mon, Feb 7, 2011 at 1:12 PM, Arihan Sinha <arihan_sinha@yahoo.com> 
> wrote:
>> Thanks for this but I am getting like
>>
>> [[300, 1], [300, 2], [301, 1], [301, 3], [301, 4], [302, 3], [302, 
>> 4]]
>
> ???
>
> irb(main):004:0> hsh = Hash.new{|h,k| h[k]=[]}
> => {}
> irb(main):005:0> keys.zip(values).each{|k,v| hsh[k] << v}
> => [[300, 1], [300, 2], [301, 1], [301, 3], [301, 4], [302, 3], [302, 
> 4]]
> irb(main):006:0> hsh
> => {300=>[1, 2], 301=>[1, 3, 4], 302=>[3, 4]}
>
>> but I actually need like
>>
>> hsh = {"300" =>["1","2"],"301" => ["1","3","4"],"302"=>["3","4"]}
>
> Btw, #zip without #each is more efficient:
>
> irb(main):007:0> hsh = Hash.new{|h,k| h[k]=[]}
> => {}
> irb(main):008:0> keys.zip(values) {|k,v| hsh[k] << v}
> => nil
> irb(main):009:0> hsh
> => {300=>[1, 2], 301=>[1, 3, 4], 302=>[3, 4]}
>
> Cheers
>
> robert

 Thanks, I never knew #zip took a block argument before.

-- 
 Alex Gutteridge