map-reduce-example.groovy

  // Groovy map-reduce example

  // declare a closure
  def half = { it ->
   it / 2
  }

  // declare another closure
  def sum = { result, i -> 
   result + i 
  }

  // initialisation of an array of numbers
  def numbers = [2, 0, 1, 7]

  // map (named collect in Groogy)
  def halfNumbers = numbers.collect(half)
  assert halfNumbers == [1, 0, 0.5, 3.5]

  // reduce (named inject in Groovy)
  def total = numbers.inject(0, sum)
  assert total == 10

An example of closure where we illustrate how we can do in Groovy map/reduce on an array.

what about filter? findAll ?

what about filter? findAll ?

@chb0github, What do you wanna do in this case?

  def total = numbers.findAll{it > 2}.grep(Number).inject(0, sum)
  assert total == 7

I asked this question long ago when I was much less knowledgable.