Example of using groupBy and collect together

gistfile1.groovy

// Example of using groupBy and collect together

def values =
[[lastname: "Anderson", age: 30],
[lastname: 'Bergstrom', age: 24],
[lastname: 'Anderson', age: 45],
[lastname: 'Bergstrom', age: 40],
[lastname: 'Brown', age: 25]]

// Find average age by lastname:
values.groupBy { it.lastname }
      .collect { key, value -> ["$key": value.age.sum()/value.size()] }