From: Daniel Finnie <dan@...>
Date: 2008-03-03T08:03:09+09:00
Subject: Re: Building your own string sorting method

A basic string sorting routine would just sort based on ASCII
codepoints (see a list at http://urltea.com/2tu7 ).

So you could do this in Ruby 1.9:

irb(main):002:0> class String
irb(main):003:1>   def <=> other
irb(main):004:2>     self.each_char.map(&:ord) <=> other.each_char.map(&:ord)
irb(main):005:2>   end
irb(main):006:1> end

<, >, ==, !=, etc. are all defined in terms of <=>, the spaceship
operator, so all of the previous operations are affected when we
define <=>.  Arrays sort by comparing the first non-matching element.

irb(main):011:0> %w[a c b g h j g p q].sort
=> ["a", "b", "c", "g", "g", "h", "j", "p", "q"]

Of course this has a lot of deficiencies:

irb(main):014:0> %w[a c b g h j g p q Z A G].sort
=> ["A", "G", "Z", "a", "b", "c", "g", "g", "h", "j", "p", "q"]

So we could downcase each character or something.

But even advanced sorting algorithms have problems -- German sorts
beta as nn or something and lots of other languages have similar
issues.  Book listings generally don't include words like "the" when
sorting, etc.  I would decide those before starting.

On Sun, Mar 2, 2008 at 5:50 PM, Joseph L. Casale
<jcasale@activenetwerx.com> wrote:
> I am trying to find examples of this to help me but can't seem to locate any on the web. Anyone know of any online examples? I know ruby has a built in method for sorting an array, but it's part of a tutorial...
>
>  Thanks!
>  jlc
>