issue_comments: 731637045

I also get this error locally. somehow in some envs xarray (but not in others) tries to use daysinmonth. I also know about days_in_month, but just changing that in frequencies.py https://github.com/pydata/xarray/blob/d9ebcafaddf0bb80052d30f43ca5ea18a5c7229f/xarray/coding/frequencies.py#L261 didnt help it.

``` ____________ test_cftimeindex_freq_in_repr[MS-noleap] _______________

freq = 'MS', calendar = 'noleap'

@requires_cftime
@pytest.mark.parametrize("calendar", ["noleap", "360_day"])
@pytest.mark.parametrize("freq", ["1D", "MS"])
def test_cftimeindex_freq_in_repr(freq,calendar):
    index = xr.cftime_range(start="2000", periods=3, freq=freq, calendar=calendar)

  assert f', freq={freq}' in index.__repr__()

/Users/aaron.spring/Coding/xarray/xarray/tests/test_cftimeindex.py:952:

---

/Users/aaron.spring/Coding/xarray/xarray/coding/cftimeindex.py:342: in repr attrs_str = format_attrs(self) /Users/aaron.spring/Coding/xarray/xarray/coding/cftimeindex.py:263: in format_attrs "freq": f"'{index.freq}'" /Users/aaron.spring/Coding/xarray/xarray/coding/cftimeindex.py:691: in freq return infer_freq(self) /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:97: in infer_freq return inferer.get_freq() /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:132: in get_freq return self._infer_daily_rule() /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:165: in _infer_daily_rule monthly_rule = self._get_monthly_rule() /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:199: in _get_monthly_rule return {"cs": "MS", "ce": "M"}.get(month_anchor_check(self.index))

---

dates = <[AttributeError("'cftime._cftime.DatetimeNoLeap' object has no attribute 'daysinmonth'",) raised in repr()] CFTimeIndex object at 0x7fca9312b160>

def month_anchor_check(dates):
    """Return the monthly offset string.

    Return "cs" if all dates are the first days of the month,
    "ce" if all dates are the last day of the month,
    None otherwise.

    Replicated pandas._libs.tslibs.resolution.month_position_check
    but without business offset handling.
    """
    calendar_end = True
    calendar_start = True

    for date in dates:
        if calendar_start:
            calendar_start &= date.day == 1

        if calendar_end:

          cal = date.day == date.daysinmonth

E AttributeError: 'cftime._cftime.DatetimeNoLeap' object has no attribute 'daysinmonth'

/Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:261: AttributeError ____________ test_cftimeindex_freq_in_repr[MS-360_day] ______________

freq = 'MS', calendar = '360_day'

@requires_cftime
@pytest.mark.parametrize("calendar", ["noleap", "360_day"])
@pytest.mark.parametrize("freq", ["1D", "MS"])
def test_cftimeindex_freq_in_repr(freq,calendar):
    index = xr.cftime_range(start="2000", periods=3, freq=freq, calendar=calendar)

  assert f', freq={freq}' in index.__repr__()

/Users/aaron.spring/Coding/xarray/xarray/tests/test_cftimeindex.py:952:

---

/Users/aaron.spring/Coding/xarray/xarray/coding/cftimeindex.py:342: in repr attrs_str = format_attrs(self) /Users/aaron.spring/Coding/xarray/xarray/coding/cftimeindex.py:263: in format_attrs "freq": f"'{index.freq}'" /Users/aaron.spring/Coding/xarray/xarray/coding/cftimeindex.py:691: in freq return infer_freq(self) /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:97: in infer_freq return inferer.get_freq() /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:132: in get_freq return self._infer_daily_rule() /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:165: in _infer_daily_rule monthly_rule = self._get_monthly_rule() /Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:199: in _get_monthly_rule return {"cs": "MS", "ce": "M"}.get(month_anchor_check(self.index))

---

dates = <[AttributeError("'cftime._cftime.Datetime360Day' object has no attribute 'daysinmonth'",) raised in repr()] CFTimeIndex object at 0x7fca930cfe10>

def month_anchor_check(dates):
    """Return the monthly offset string.

    Return "cs" if all dates are the first days of the month,
    "ce" if all dates are the last day of the month,
    None otherwise.

    Replicated pandas._libs.tslibs.resolution.month_position_check
    but without business offset handling.
    """
    calendar_end = True
    calendar_start = True

    for date in dates:
        if calendar_start:
            calendar_start &= date.day == 1

        if calendar_end:

          cal = date.day == date.daysinmonth

E AttributeError: 'cftime._cftime.Datetime360Day' object has no attribute 'daysinmonth'

/Users/aaron.spring/Coding/xarray/xarray/coding/frequencies.py:261: AttributeError ===================================================================================== short test summary info ===================================================================================== FAILED xarray/tests/test_cftimeindex.py::test_cftimeindex_freq_in_repr[1D-noleap] - AttributeError: 'cftime._cftime.DatetimeNoLeap' object has no attribute 'daysinmonth' FAILED xarray/tests/test_cftimeindex.py::test_cftimeindex_freq_in_repr[1D-360_day] - AttributeError: 'cftime._cftime.Datetime360Day' object has no attribute 'daysinmonth' FAILED xarray/tests/test_cftimeindex.py::test_cftimeindex_freq_in_repr[MS-noleap] - AttributeError: 'cftime._cftime.DatetimeNoLeap' object has no attribute 'daysinmonth' FAILED xarray/tests/test_cftimeindex.py::test_cftimeindex_freq_in_repr[MS-360_day] - AttributeError: 'cftime._cftime.Datetime360Day' object has no attribute 'daysinmonth' ======================================================================================== 4 failed in 2.58s =========================================================================== ```