This page contains automated test results for code from O'Reilly's Ruby Cookbook. If this code looks interesting or useful, you might want to buy the whole book.

Getting the n Smallest Items of an Array
CodeExpectedActual
[3, 5, 11, 16].min
 3 3 
["three", "five", "eleven", "sixteen"].min
 "eleven" "eleven" 
["three", "five", "eleven", "sixteen"].min { |x,y| x.size <=> y.size }
 "five" "five" 
[3, 5, 11, 16].max
 16 16 
["three", "five", "eleven", "sixteen"].max
 "three" "three" 
["three", "five", "eleven", "sixteen"].max { |x,y| x.size <=> y.size }
 "sixteen" "sixteen" 
l = [1, 60, 21, 100, -5, 20, 60, 22, 85, 91, 4, 66]
sorted = l.sort
#The top 5
sorted[-5...sorted.size]
 [60, 66, 85, 91, 100] [60, 66, 85, 91, 100] 
#The bottom 5
sorted[0...5]
 [-5, 1, 4, 20, 21] [-5, 1, 4, 20, 21] 
require 'sortedarray'
module Enumerable
  def min_n(n, &block)
    block ||= proc { |x,y| x <=> y } 
    stable = SortedArray.new(&block)
    each do |x| 
    stable << x if stable.size < n or block.call(x, stable[-1]) == -1
      stable.pop until stable.size <= n
    end
    return stable
  end
  def max_n(n, &block)
    block ||= proc { |x,y| x <=> y }
    stable = SortedArray.new(&block)
    each do |x| 
      stable << x if stable.size < n or block.call(x, stable[0]) == 1
      stable.shift until stable.size <= n
    end
    return stable
  end
end
l = [1, 60, 21, 100, -5, 20, 60, 22, 85, 91, 4, 66]
l.max_n(5)
 
[60, 66, 85, 91, 100]
 
Error! (Exception?) Here's stdout:
LoadError: no such file to load -- sortedarray
	from (irb):13:in `require'
	from (irb):13
NameError: uninitialized constant Enumerable::SortedArray
	from (irb):26:in `max_n'
	from (irb):35

l.min_n(5)
 
[-5, 1, 4, 20, 21]
 
Error! (Exception?) Here's stdout:
NameError: uninitialized constant Enumerable::SortedArray
	from (irb):17:in `min_n'
	from (irb):36

l.min_n(5) { |x,y| x.abs <=> y.abs }
 
[1, 4, -5, 20, 21]
 
Error! (Exception?) Here's stdout:
NameError: uninitialized constant Enumerable::SortedArray
	from (irb):17:in `min_n'
	from (irb):37