Function _legacy_to_new_freq

xarray/coding/cftime_offsets.py:1505–1550

(freq: T_FreqStr)

def _legacy_to_new_freq(freq: T_FreqStr) -> T_FreqStr:
    # to avoid internal deprecation warnings when freq is determined using pandas < 2.2

    # TODO: remove once requiring pandas >= 2.2

    if not freq or Version(pd.__version__) >= Version("2.2"):
        return freq

    try:
        freq_as_offset = to_offset(freq, warn=False)
    except ValueError:
        # freq may be valid in pandas but not in xarray
        return freq

    if isinstance(freq_as_offset, MonthEnd) and "ME" not in freq:
        freq = freq.replace("M", "ME")
    elif isinstance(freq_as_offset, QuarterEnd) and "QE" not in freq:
        freq = freq.replace("Q", "QE")
    elif isinstance(freq_as_offset, YearBegin) and "YS" not in freq:
        freq = freq.replace("AS", "YS")
    elif isinstance(freq_as_offset, YearEnd):
        if "A-" in freq:
            # Check for and replace "A-" instead of just "A" to prevent
            # corrupting anchored offsets that contain "Y" in the month
            # abbreviation, e.g. "A-MAY" -> "YE-MAY".
            freq = freq.replace("A-", "YE-")
        elif "Y-" in freq:
            freq = freq.replace("Y-", "YE-")
        elif freq.endswith("A"):
            # the "A-MAY" case is already handled above
            freq = freq.replace("A", "YE")
        elif "YE" not in freq and freq.endswith("Y"):
            # the "Y-MAY" case is already handled above
            freq = freq.replace("Y", "YE")
    elif isinstance(freq_as_offset, Hour):
        freq = freq.replace("H", "h")
    elif isinstance(freq_as_offset, Minute):
        freq = freq.replace("T", "min")
    elif isinstance(freq_as_offset, Second):
        freq = freq.replace("S", "s")
    elif isinstance(freq_as_offset, Millisecond):
        freq = freq.replace("L", "ms")
    elif isinstance(freq_as_offset, Microsecond):
        freq = freq.replace("U", "us")

    return freq


def date_range_like(source, calendar, use_cftime=None):