From: James Edward Gray II <james@...>
Date: 2006-12-07T23:21:31+09:00
Subject: Re: [Puzzle] How to do parameter variation?

On Dec 7, 2006, at 1:25 AM, Gary Boone wrote:

>
> Suppose you want to do several runs of a program or function, varying
> the parameters each time. You start with a hash of parameter lists:
>
>     params = { speed=>[1,2,3], beta=>[0.1, 0.002, 0.4], x=>['a',  
> 'b'] }
>
> Given this set, you'll call the test function 18 times:
>
>    test_function( {speed=>1, beta=>0.1, x=>'a'} )
>    test_function( {speed=>1, beta=>0.1, x=>'b'} )
>    test_function( {speed=>1, beta=>0.002, x=>'a'} )
>    ... etc

See if this gives you some ideas:

#!/usr/bin/env ruby -w

def call_with(meth, params, selected = Hash.new)
   params  = params.dup
   key     = params.keys.sort_by { |k| k.to_s }.first
   choices = params.delete(key)

   choices.each do |choice|
     selected = selected.merge(key => choice)
     if params.empty?
       send(meth, selected)
     else
       call_with(meth, params, selected)
     end
   end
end

def print_args(args)
   p args
end

call_with :print_args, :speed => [1, 2, 3],
                        :beta  => [0.1, 0.002, 0.4],
                        :x     => ["a", "b"]
# >> {:speed=>1, :beta=>0.1, :x=>"a"}
# >> {:speed=>1, :beta=>0.1, :x=>"b"}
# >> {:speed=>2, :beta=>0.1, :x=>"a"}
# >> {:speed=>2, :beta=>0.1, :x=>"b"}
# >> {:speed=>3, :beta=>0.1, :x=>"a"}
# >> {:speed=>3, :beta=>0.1, :x=>"b"}
# >> {:speed=>1, :beta=>0.002, :x=>"a"}
# >> {:speed=>1, :beta=>0.002, :x=>"b"}
# >> {:speed=>2, :beta=>0.002, :x=>"a"}
# >> {:speed=>2, :beta=>0.002, :x=>"b"}
# >> {:speed=>3, :beta=>0.002, :x=>"a"}
# >> {:speed=>3, :beta=>0.002, :x=>"b"}
# >> {:speed=>1, :beta=>0.4, :x=>"a"}
# >> {:speed=>1, :beta=>0.4, :x=>"b"}
# >> {:speed=>2, :beta=>0.4, :x=>"a"}
# >> {:speed=>2, :beta=>0.4, :x=>"b"}
# >> {:speed=>3, :beta=>0.4, :x=>"a"}
# >> {:speed=>3, :beta=>0.4, :x=>"b"}

James Edward Gray II