Windowed Aggregation

Given a list of dictionaries, add a rank field to each row based on the value of a specified column within each group (partition). Rank 1 is the highest value. Ties receive the same rank.

Example

data = [
  {"dept": "eng", "name": "Alice", "score": 90},
  {"dept": "eng", "name": "Bob", "score": 80},
  {"dept": "sales", "name": "Carol", "score": 95}
]
rank_within_group(data, "dept", "score")
# => [
#   {"dept": "eng", "name": "Alice", "score": 90, "rank": 1},
#   {"dept": "eng", "name": "Bob", "score": 80, "rank": 2},
#   {"dept": "sales", "name": "Carol", "score": 95, "rank": 1}
# ]