Group By and Aggregate

Given a list of dictionaries, group the data by a specified column and compute the sum of another column for each group.

Example

data = [
  {"dept": "eng", "salary": 100},
  {"dept": "eng", "salary": 200},
  {"dept": "sales", "salary": 150}
]
group_by_sum(data, "dept", "salary")
# => {"eng": 300, "sales": 150}