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How to Group Rows by Key into Nested Arrays in Python

This code groups rows in a list of dictionaries by a specified key and returns a dictionary with each key mapped to a list of values from another key.

grouping defaultdict data-aggregation

Python

from collections import defaultdict


def implode_rows(rows, key, value_key):
    grouped = defaultdict(list)
    for row in rows:
        grouped[row[key]].append(row[value_key])
    return dict(grouped)


if __name__ == "__main__":
    data = [
        {"category": "fruit", "item": "apple"},
        {"category": "fr…

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