From: James Herdman <james.herdman@...>
Date: 2008-11-10T23:34:49+09:00
Subject: Re: replace values in hash

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Not bad. Let's tighten it up a little:

class Hash
  def replace_value(old, new)
    self.inject({}) do |result, (key, existing_value)|
      result[key] = (value == old) ? new : existing_value
      result
    end
  end
end

This isn't bad, but you wouldn't want to do this for large Hashes since you
end up copying the original.

James

On Wed, Nov 5, 2008 at 12:38 PM, Brian Adkins <lojicdotcom@gmail.com> wrote:

> Jason Lillywhite <jason.lillywhite@gmail.com> writes:
>
> > how would I iterate over a hash, such as
> >
> > x = { 'a' => "hi", 'b' => nil, 'c' => "do"}
> >
> > and replace nil values with 'foo' then return the hash again?
>
> ~/temp$ cat -b temp.rb
>     1  require 'pp'
>
>     2  class Hash
>     3    def replace_value old, new
>     4      self.inject({}) do |result,pair|
>     5        k, v = pair[0], pair[1]
>     6        result[k] = (v == old) ? new : v
>     7        result
>     8      end
>     9    end
>    10  end
>
>    11  x = { 'a' => "hi", 'b' => nil, 'c' => "do", :d => nil }
>    12  pp x
>    13  y = x.replace_value(nil, 'foo')
>    14  pp y
> ~/temp$ ruby temp.rb
> {"a"=>"hi", "b"=>nil, :d=>nil, "c"=>"do"}
> {"a"=>"hi", "b"=>"foo", "c"=>"do", :d=>"foo"}
>
> --
> Brian Adkins
> http://www.lojic.com/
> http://lojic.com/blog/
>
>

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