datetime chunking

chunks.py

import datetime as dt
from functools import partial
from typing import Any

import pandas as pd
from dateutil import relativedelta


def next_chunk(st: pd.Timestamp, et: pd.Timestamp, freqs: list[Any]):
    if st == et:
        return []
    if not freqs:
        return [(st, et)]

    chunks = list(pd.date_range(st, et, freq=freqs[0](normalize=True)))
    if not chunks:
        return next_chunk(st, et, freqs[1:])

    st_chunks = next_chunk(st, chunks[0], freqs[1:])
    et_chunks = next_chunk(chunks[-1], et, freqs[1:])

    res = [
        *st_chunks,
        *((chunks[i], chunks[i + 1]) for i in range(len(chunks) - 1)),
        *et_chunks,
    ]
    return res


if __name__ == "__main__":
    stt = dt.datetime(2022, 2, 22, 15, 0, tzinfo=dt.timezone.utc)
    ett = dt.datetime(2024, 11, 20, 15, 0, tzinfo=dt.timezone.utc)
    qchunks = next_chunk(
        pd.Timestamp(stt),
        pd.Timestamp(ett),
        [
            pd.offsets.YearBegin,
            partial(pd.offsets.QuarterBegin, startingMonth=1),
            pd.offsets.MonthBegin,
        ],
    )