From: Austin Ziegler <halostatue@...>
Date: 2008-05-15T00:04:17+09:00
Subject: Re: changing hash key

On Wed, May 14, 2008 at 10:53 AM, Tim Wolak <tim.wolak@gmail.com> wrote:
> I've been looking for a way to change a hash key.  In my code I'm trying
> to change the key from a number to a string.  Do I need to convert the
> key to a string and put it new value in there or is my code wrong?

>  def numbers
>                  @skty = Hash.new(0)
>                  @sktynl.each do |key, value|
>                    if key <= "39"
>                      key = "SKTY"
>                      @skty[key] += value # !> instance variable @skty
> not initialized
>                    elsif key >="40"
>                      key = "SKYNY"
>                      @skty[key] += value
>                    end

First, your comparison isn't against numbers, but against strings:

  irb(main):001:0> "5" <= "40"
  => false

If your keys are truly numbers, use numeric comparisons.

Second, I suspect the problem isn't that @skty (which is a *really*
bad variable name, by the way) isn't initialized, but that @skty[key]
isn't initialized. Which is true because you're not initializing the
value, you're just providing a default value if the key isn't found.

If you need to initialize an unfound value, you need the block form of Hash.new:

   @skty = Hash.new { |h, k| h[k] = 0 }

-austin
-- 
Austin Ziegler * halostatue@gmail.com * http://www.halostatue.ca/
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