From: ES <ruby-ml@...>
Date: 2005-10-17T07:33:57+09:00
Subject: Re: how to create a hash from 2 arrays?

Tiggerius wrote:
> keys = ["1", "2", "3", "4", "5"]
> vals = ["a", "b", "c", "d", "e", "f", "g"]
> 
> I want h = {"1"=>"a", "2"=>"b", "3"=>"c", "4"=>"d", "5"=>"e"}
> 
> right now I do it by:
>   for i in 0..keys.size-1
>     h[keys[i]]=vals[i]
>   end
> 
> is there a ruby way, more slick way of doing this? Thanks.

Array#zip is a good way to get started. It takes two Arrays and
'zips' them together: [1].zip([2])  =>  [[1, 2]]. #inject can be
used to accumulate data, here we accumulate into the Hash (which
is the initial {} there):

   keys.zip(values).inject({}) {|hash, (k, v)| hash[k] = v; hash}

An alternative syntax would leverage the ability of Hash.[] to
take an even number of parameters and construct its keys and
values from that: Hash[1, 2] => {1 => 2}. To create separate
parameters from the contents of an Array, use the splat-operator
(*): *[1, 2]  =>  1, 2:

   Hash[*keys.zip(values).flatten]

This only works when you do not have nested Arrays, though.

E