From: Gary Wright <gwtmp01@...>
Date: 2007-12-09T07:48:46+09:00
Subject: Re: Putting value in sorted array


On Dec 8, 2007, at 3:27 PM, Jari Williamsson wrote:
> Thanks for the tip! I optimized it into:
>
> arr = [5, 3, 1]
> insert_value = 2
> arr.sort! { |a,b| b <=> a } if !(arr << insert_value).uniq!

That is a lot of work to insert an item into a sorted array.

Ruby 1.9 has find_index which makes it easy to locate an
insert position.  Based on that here are some ideas:

class Array
   if RUBY_VERSION < "1.9.0"
     def find_index(miss=nil)
       each_with_index { |e,i| return i if yield(e) }
       miss
     end
   end

   def insert_when(x)
     pos = find_index { |e| yield(e, x) }
     insert(pos, x) if pos
     self
   end
end

a = [1,3,5]

a.insert_when(4) {|e, x| e >= x }    # [1,3,4,5]
a.insert_when(4) {|e, x| e >= x }    # [1,3,4,4,5]

a.insert_when(3) {|e, x|
   break if e == x
   e > x
}                                    # [1,3,4,4,5]