From: Martin DeMello <martindemello@...>
Date: 2012-05-02T12:41:36+09:00
Subject: Re: Overwriting one Ruby array or arrays with another

On Tue, May 1, 2012 at 8:27 PM, Craig Law <lists@ruby-forum.com> wrote:
> If I can produce a hash of {[x, y] => xxxxx } which holds the values "X"
> and "20120501" that would be OK with me.
>
> Would the code for such a hash be something like this ...
>
> {[1, 1] => ["X", "20120501"]}
> {[1, 2] => ["O", "20120502"]}
>
> ... and if so how would I overwrite one hash with the other?

The built-in hash.update method will do this:

ruby-1.9.2-p0 > a = {[1, 1] => "x", [1, 2] => "x", [1, 3] => "x", [2,
1] => "x", [2, 3] => "x", [3, 3] => "x"}
 => {[1, 1]=>"x", [1, 2]=>"x", [1, 3]=>"x", [2, 1]=>"x", [2, 3]=>"x",
[3, 3]=>"x"}

ruby-1.9.2-p0 > b = {[1, 1] => "o", [2, 2] => "o", [3, 3] => "o"}
 => {[1, 1]=>"o", [2, 2]=>"o", [3, 3]=>"o"}

ruby-1.9.2-p0 > a.update(b)
 => {[1, 1]=>"o", [1, 2]=>"x", [1, 3]=>"x", [2, 1]=>"x", [2, 3]=>"x",
[3, 3]=>"o", [2, 2]=>"o"}

ruby-1.9.2-p0 > a
 => {[1, 1]=>"o", [1, 2]=>"x", [1, 3]=>"x", [2, 1]=>"x", [2, 3]=>"x",
[3, 3]=>"o", [2, 2]=>"o"}

Note that this will also fill in "o"s in cells that did not have an "x" in them.

martin