From: Massimiliano Mirra <list@...>
Date: 2002-11-16T02:09:28+09:00
Subject: Re: Ruby equivalent to Python's map()?

On Thu, Nov 14, 2002 at 10:39:44PM +0900, Roberto Amorim wrote:
> The first parameter above can be any function taking 2 parameters and
> returning a tuple. A ruby equivalent would be something of the form:
> 
> map(a,b) {|i,j| i,j}

Just a quick hack, but you can use this:

class Array
  def zip(*arrays)
    zipped = []
    all = [self, *arrays]
    max_length = all.collect {|a| a.length}.max

    0.upto(max_length-1) do |i|
      zipped << all.collect {|a| a[i]}
    end
    return zipped
  end

  def each2(*arrays, &block)
    zip(*arrays).each(&block)
  end

  def collect2(*arrays, &block)
    zip(*arrays).collect(&block)
  end
end

a = [1, 2, 3]
b = [4, 5, 6]
c = [7, 8, 9]

a.each2(b) {|i, j| ...}
a.each2(b, c) {|i, j, k| ...}


collect2 just behaves as you'd expect it to.


Massimiliano