groupBy
Group the data based on key/value.
var alice = {name: 'Alice', grade: 'A'};
var bob = {name: 'Bob', grade: 'C'};
var claude = {name: 'Claude', grade: 'A'};
var data = [alice, bob, claude];
g.groupBy(data, 'grade');
Parameters
data: The input data, as a list of objects.key: The key to group by.