DZone Snippets: arrays code

randomizing an array in ruby (the right way)

sikelianos (Zeke Sikelianos) — Mon, 15 Oct 2007 18:09:53 GMT

Snagged from http://www.rubyquiz.com/quiz113.html



# be sure to use sort_by rather than sort

quiz = (1..10).to_a

quiz.sort_by { rand }

Generic 'sum' and 'mean' methods for Ruby arrays

peter (Peter Cooperx) — Thu, 08 Jun 2006 20:19:04 GMT

class Array; def sum; inject( nil ) { |sum,x| sum ? sum+x : x }; end; end

It's class agnostic, so you can do this:

[1,2,3].sum              # => 6

['a','b','c'].sum        # => 'abc'

[['a'], ['b','c']].sum   # => ['a', 'b', 'c']

You can then add a 'mean' operator easily:

class Array; def mean; sum / size; end; end

mean only works for numbers though, of course, like so:

[1,2,1000].mean # => 334

That said, if your class implements division, it'll also work!

Maybe UnSerialize

MellerTime (Chris Meller) — Mon, 20 Feb 2006 08:09:13 GMT

Checks to see if a string is actually the serialized version of an array. If it is, we return an unserialized version. If not, return the original string. This way, we can just call our function on stored DB values and not worry about checking the results.

This was snagged from the Wordpress 2.0 source. Yayyy for Open Source!



	function maybe_unserialize ( $original ) {

		if ( false !== $gm = @ unserialize($original) )

			return $gm;

		else

			return $original;

	}

Swap elements of an array in Ruby

peter (Peter Cooperx) — Fri, 13 May 2005 09:29:45 GMT

class Array

    def swap!(a,b)

         self[a], self[b] = self[b], self[a]

    self

    end

end

You can now do stuff like..

[1,2,3,4].swap!(2,3) # = [1,2,4,3] etc..

Many thanks to Sam Stephenson and technoweenie for their suggestions.