Source code for rook.utils.fixes_utils

import xarray as xr
import cftime




def convert_calendar_to_gregorian(ds: xr.Dataset, reference_date="1850-01-01") -> xr.Dataset:
    """
    Convert a Dataset from proleptic_gregorian to gregorian calendar, including time_bnds if present.

    Parameters
    ----------
    - ds (xarray.Dataset): Input dataset with time coordinate using proleptic_gregorian calendar.
    - reference_date (str): Time units origin (e.g., '1850-01-01').

    Returns
    -------
    - xarray.Dataset: A new dataset with calendar set to 'gregorian'.
    """
    # ds = ds.copy(deep=True)  # avoid modifying original

    # Convert time coordinate
    original_time = ds.time.values
    new_time = [cftime.DatetimeGregorian(t.year, t.month, t.day, t.hour, t.minute, t.second) for t in original_time]
    ds = ds.assign_coords(time=("time", new_time))

    # Convert time_bnds if present
    if "time_bnds" in ds:
        bnds = ds["time_bnds"].values  # shape: (time, 2)
        new_bnds = []
        for start, end in bnds:
            new_start = cftime.DatetimeGregorian(start.year, start.month, start.day,
                                                 start.hour, start.minute, start.second)
            new_end = cftime.DatetimeGregorian(end.year, end.month, end.day,
                                               end.hour, end.minute, end.second)
            new_bnds.append([new_start, new_end])
        ds["time_bnds"].values = new_bnds
        ds["time_bnds"].encoding.update({
            "calendar": "gregorian",
            "units": f"days since {reference_date}",
            "dtype": "float64"
        })

    # Update time encoding
    ds.time.encoding.update({
        "calendar": "gregorian",
        "units": f"days since {reference_date}",
        "dtype": "float64"
    })

    return ds