From: 7stud -- <bbxx789_05ss@...>
Date: 2008-02-07T09:03:40+09:00
Subject: Re: Array Practice

Adam Akhtar wrote:
> As some of you may know from previous threads im trying to practice
> specific areas of ruby. One simple exercise i set myself was taking a
> elements in an array such as
> 
> [1,2,3,1,2,2,4,3,2,1]
> 
> and then grouping them together and putting them in subarrays within an
> array like this
> 
> [ [1,1,1], [2,2,2,2] , [3,3] ,[4] ]
> 
> Heres how i did it (im new to both programming and ruby)
> 
> def subpack(list)
>   uniqlist = Array.new
>   subpacklist = Array.new
>   list.sort!
> 
>   uniqlist = list.uniq
>   uniqlist.each_index do |i|
>     rangeleft = list.index(uniqlist[i])
>     rangeright = list.rindex(uniqlist[i])
>     subpacklist << list.slice(rangeleft..rangeright)
>   end
>   subpacklist
> end
> 
> 
> WITHOUT GIVING ME YOUR SOLUTION IN FULL, how could i improve this...
> i.e. give me some hints, the names of some methods but not the solution
> as i want a go myself. 

Another way would be to iterate over your original array and add each 
number to a Hash as you go.   A Hash keys will be one of the numbers, 
and the corresponding value will be an array containing all of that 
particular number.

You can create a new Hash so that when you access a non existent key in 
a Hash an empty array will be returned.  See the block form of 
Hash.new().

Finally, you can create your final array from the hash values using 
Hash#values.

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