From: barjunk <barjunk@...>
Date: 2007-07-13T02:55:24+09:00
Subject: Re: Returning part of a hash

On Jul 11, 11:57 pm, "Robert Klemme" <shortcut...@googlemail.com>
wrote:
> 2007/7/11, barjunk <barj...@attglobal.net>:
>
>
>
> > I have hash that has about 20 keys.  I'd like to create a new variable
> > with just three of those keys.  Example:
>
> > hash = { "key1" => "value1",
> >                "key2" => "value2",
> >                ...
> >                "key20" => "value20" }
>
> > And a function like:
> > newhash = hash.slice("key2","key5","key7")
>
> > Which creates:
>
> > newhash = { "key2" => "value1",
> >                "key5" => "value5",
> >                "key7" => "value7" }
>
> > hash.select {|key, value| key == "key1" }
>
> > I could do the above multiple times, but this returns an array not the
> > hash pair.
>
> irb(main):001:0> h={}
> => {}
> irb(main):002:0> 20.times {|i| h["key#{i}"]="val#{i}"}
> => 20
>
> irb(main):008:0> h2 = Hash[*h.select {|k,v| %w{key1 key5
> key8}.include? k}.flatten]
> => {"key1"=>"val1", "key5"=>"val5", "key8"=>"val8"}
>
> irb(main):013:0> h.dup.delete_if {|k,v| not %w{key1 key5 key8}.include? k}
> => {"key1"=>"val1", "key5"=>"val5", "key8"=>"val8"}
>
> Kind regards
>
> robert

WOW!

Thanks for all the options...I didn't understand the O(n^2)
conversation other than that there is a possibility for the time it
takes to get the pieces would get bigger as the array got bigger.

Mike B.