From: Dave Thomas <Dave@...>
Date: 2000-11-27T09:51:21+09:00
Subject: [ruby-talk:6585] Re: best way to interleaf arrays?

David Alan Black <dblack@candle.superlink.net> writes:

> Is there a nice Ruby idiom for interleafing arrays?  It's not hard to
> write a method that will do it, but I'd be interested in knowing how
> it's been done in the past.

Matz has a technique for simulating external iterators using threads,
which would do it.

You could also do it the boring way:

     def interleave(a1, a2)
       n = a1.size
       n = a2.size if a2.size < n
       (0...n).collect {|i| [a1[i], a2[i]]}.flatten + a1[n..-1] + a2[n..-1]
     end

On the Hash front, I'm starting to think it would be useful to have

   Hash.from_array(ary, value)

which was equivalent to

   def Hash.from_array(ary, value = 1)
      h = {}
      if block_given?
        ary.each {|k| h[k] = yield(k,value) }
      else
        ary.each {|k| h[k] = value }
      end
      h
   end


Regards


Dave