def cftime_start_time(date, freq):
"""Get the cftime.datetime for the start of a period.
As we are not supplying actual period objects, assumptions regarding the period are made based on
the given freq. IMPORTANT NOTE: this function cannot be used on greater-than-day freq that start at the
beginning of a month, e.g. 'MS', 'QS', 'AS' -- this mirrors pandas behavior.
Parameters
----------
date : cftime.datetime
The original datetime object as a proxy representation for period.
freq : str
String specifying the frequency/offset such as 'MS', '2D', 'H', or '3T'
Returns
-------
cftime.datetime
The starting datetime of the period inferred from date and freq.
"""
freq = to_offset(freq)
if isinstance(freq, (YearBegin, QuarterBegin, MonthBegin)):
raise ValueError("Invalid frequency: " + freq.rule_code())
if isinstance(freq, YearEnd):
month = freq.month
return date - YearEnd(n=1, month=month) + pydt.timedelta(days=1)
if isinstance(freq, QuarterEnd):
month = freq.month
return date - QuarterEnd(n=1, month=month) + pydt.timedelta(days=1)
if isinstance(freq, MonthEnd):
return date - MonthEnd(n=1) + pydt.timedelta(days=1)
return date
return str(param)
@pytest.fixture(params=_CFTIME_CALENDARS)
def calendar(request):
return request.param
@pytest.mark.parametrize(
("offset", "expected_n"),
[
(BaseCFTimeOffset(), 1),
(YearBegin(), 1),
(YearEnd(), 1),
(QuarterBegin(), 1),
(QuarterEnd(), 1),
(BaseCFTimeOffset(n=2), 2),
(YearBegin(n=2), 2),
(YearEnd(n=2), 2),
(QuarterBegin(n=2), 2),
(QuarterEnd(n=2), 2),
],
ids=_id_func,
)
def test_cftime_offset_constructor_valid_n(offset, expected_n):
assert offset.n == expected_n
@pytest.mark.parametrize(
("offset", "invalid_n"),
[
"""Called on each parameter passed to pytest.mark.parametrize"""
return str(param)
@pytest.fixture(params=_CFTIME_CALENDARS)
def calendar(request):
return request.param
@pytest.mark.parametrize(
('offset', 'expected_n'),
[(BaseCFTimeOffset(), 1),
(YearBegin(), 1),
(YearEnd(), 1),
(QuarterBegin(), 1),
(QuarterEnd(), 1),
(BaseCFTimeOffset(n=2), 2),
(YearBegin(n=2), 2),
(YearEnd(n=2), 2),
(QuarterBegin(n=2), 2),
(QuarterEnd(n=2), 2)],
ids=_id_func
)
def test_cftime_offset_constructor_valid_n(offset, expected_n):
assert offset.n == expected_n
@pytest.mark.parametrize(
('offset', 'invalid_n'),
[(BaseCFTimeOffset, 1.5),
(YearBegin, 1.5),