Use GROUP_BY to group an array of objects by a key.

Example:

employees = [
  { "name": "Alice", "office": "Dublin" },
  { "name": "Bob", "office": "Dublin" },
  { "name": "Charlie", "office": "New York" },
  { "name": "Dave", "office": "New York" }
]

GROUP_BY(employees, "office")

Returns:

{
  "Dublin": [
    { "name": "Alice", "office": "Dublin" },
    { "name": "Bob", "office": "Dublin" }
  ],
  "New York": [
    { "name": "Charlie", "office": "New York" },
    { "name": "Dave", "office": "New York" }
  ]
}

For more information, see our documentation.