From: Logan Capaldo <logancapaldo@...>
Date: 2006-03-07T08:26:20+09:00
Subject: Re: What is the best way to iterate through two containers of the same length?

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On Mar 6, 2006, at 5:17 PM, Wilson Bilkovich wrote:

>
> One way I'm fond of is:
> require 'generator'
> enum = SyncEnumerator.new([1,2,3], [7,8,9])
> enum.each do |pair|
>   puts pair.inspect
> end
> # Results in:
> [1, 7]
> [2, 8]
> [3, 9]

Warning, SyncEnumerator is slow, and you probably don't need it   
since #zip is in enumerable.
Run the below for a demonstration. Original I had it run each  
benchmark 10 times by the way, but I never had the patience to let  
the syncenum versions finish:

% cat zip_vs_syncenum.rb
require 'benchmark'
require 'generator'
a = (1..100)
b = a.to_a.reverse

puts "Using zip:"
Benchmark.bm { |x|
   x.report {
     3.times { a.zip(b) { |x, y| z = x * y } }
   }
}
puts "Using SyncEnumerator(new every time):"
Benchmark.bm { |x|
   x.report {
     3.times {
       a_b_enum = SyncEnumerator.new(a, b)
       a_b_enum.each { |x, y| z = x * y }
     }
   }
}

puts "Using SyncEnumerator(only one created):"
Benchmark.bm { |x|
   x.report {
     a_b_enum = SyncEnumerator.new(a, b)
     3.times { a_b_enum.each { |x, y| z = x * y } }
   }
}

__END__



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