Groovy example for map, filter, reduce

map-filter-reduce-example.groovy

// In Groovy
// collect = "map"
// inject = "reduce"
// 
// See http://docs.groovy-lang.org/next/html/documentation/working-with-collections.html for docs

////////////////////////////////////////////////////////////////////////////////
// Arrays 
def myNumbers = [3, 5, 1]

// Map example
def biggerNumbers = myNumbers.collect({ x ->
  x + 4
})
assert biggerNumbers == [7, 9 , 5]

// Filter example
assert [1, 2, 3].findAll { it > 1 } == [2, 3]

// Reduce example
def total = myNumbers.inject(0, { result, x ->
  result + x
})
assert total == 9

// combined example
def otherTotal = myNumbers.collect({ x ->
  x + 1
}).inject(0, { result, x ->
  result + x
})
assert otherTotal == 12

////////////////////////////////////////////////////////////////////////////////
// Dictionaries
def pets = [
  dogs: 2,
  cats: 1,
  parrots: 0,
]

// Map example
def petKinds = pets.collect({ kind, count ->
  kind
})
assert petKinds == ["dogs", "cats", "parrots"]

// Filter example
def petsThatExist = pets.findAll({ kind, count ->
  count > 0
}).collect({ kind, count ->
  kind
})
assert petsThatExist == ["dogs", "cats"]

// Reduce example
def totalPets = pets.inject(0, {result, kind, count ->
  result + count
})
assert totalPets == 3