pandas groupby to nested json

Question

I often use pandas groupby to generate stacked tables. But then I often want to output the resulting nested relations to json. Is there any way to extract a nested json fil

Answer 1

I'm aware this is an old question, but I came across the same issue recently. Here's my solution. I borrowed a lot of stuff from chrisb's example (Thank you!).

This has the advantage that you can pass a lambda to get the final value from whatever enumerable you want, as well as for each group.

from collections import defaultdict

def dict_from_enumerable(enumerable, final_value, *groups):
    d = defaultdict(lambda: defaultdict(dict))
    group_count = len(groups)
    for item in enumerable:
        nested = d
        item_result = final_value(item) if callable(final_value) else item.get(final_value)
        for i, group in enumerate(groups, start=1):
            group_val = str(group(item) if callable(group) else item.get(group))
            if i == group_count:
                nested[group_val] = item_result
            else:
                nested = nested[group_val]
    return d

In the question, you'd call this function like:

dict_from_enumerable(grouped.itertuples(), 'amount', 'year', 'office', 'candidate')

The first argument can be an array of data as well, not even requiring pandas.