From: Robert Klemme <shortcutter@...>
Date: 2010-08-20T20:07:54+09:00
Subject: Re: Need help with hash.to_s for enumerated items

2010/8/20 Sem Ptiri <rubyforum@chthonic.co.za>:
> I have a grid with keys
>
> grid.keys
> => [[1, 2], [0, 0], [3, 3], [2, 1], [1, 1], [0, 3], [3, 2], [2, 0], [1,
> 0], [0, 2], [3, 1], [2, 3], [4, 3], [3, 0], [2, 2], [1, 3], [0, 1], [6,
> 3]]
>
> I need to create a list list of all possible combinations.

Combinations of what?  Combinations of all Arrays that are your keys
or of all elements in those arrays or...?

> I would start
> by taking the first item, then linking it with every other item, then
> truncate the first item, and repeat.

"Truncate"?

> My problem is that on
>
> grid.keys[0].to_s
> => "12"
>
> it mashes the [1, 2] together making it unusable.

I have no idea what Array#to_s has to do in combining elements.

> Could you suggest a better data structure for storing a list of all
> possible combinations?

Why not use an Array of Arrays?

> Linking a hash [1, 2] to [0, 0] and then [1, 1] would simply override
> the previous link.

What exactly do you mean by "linking"?  Are you talking about
replacing a hash key?  Or are you talking about using a Hash key as
value of another key?

As soon as you set another value for the same Hash key the old value is gone:

irb(main):003:0> h={}
=> {}
irb(main):004:0> h[[1,2]]=[0,0]
=> [0, 0]
irb(main):005:0> h
=> {[1, 2]=>[0, 0]}
irb(main):006:0> h[[1,2]]=[1,1]
=> [1, 1]
irb(main):007:0> h
=> {[1, 2]=>[1, 1]}

Kind regards

robert


-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/