def cesm_time_from_bnds(xr_data, min_year=1701):
"""
Use mid-points from time_bnds in CESM output data to populate time dimension with
numpy.datetime64 values.
Args:
xr_data: xarray Dataset containing CESM output data.
min_year: integer specifying minimum year to accept for reference date, derived from units.
If the reference year is less than min_year, then the reference year will be changed to
min_year. This allows dates to be shifted to be greater than e.g. 1678. (default 1701)
Returns:
Copy of xr_data, with modified time and time_bnds dimensions.
"""
data = xr_data.copy()
try:
time_bnds_mid = data['time_bnds'].mean(dim='bnds')
except ValueError:
try:
time_bnds_mid = data['time_bnds'].mean(dim='nb2')
except ValueError:
time_bnds_mid = data['time_bnds'].mean(dim='nbnd')
data['time'].values = climapy.dt_convert_to_datetime64(
time_bnds_mid,
units=data['time'].units,
calendar=data['time'].calendar,
min_year=min_year)
data['time_bnds'].values = climapy.dt_convert_to_datetime64(
data['time_bnds'],
units=data['time'].units,
calendar=data['time'].calendar,
min_year=min_year)
return data
def test_365_day_with_float(self):
result = climapy.dt_convert_to_datetime64(
365. * 1970 + 1.5,
units='days since 1-1-1 00:00:00',
calendar='365_day')
correct = np.datetime64('1971-01-02T12:00:00')
assert result == correct
def test_365_day_with_array(self):
result = climapy.dt_convert_to_datetime64(
np.array([3648., 3650., 3652.]),
units='days since 2000-01-01 00:00:00',
calendar='365_day')
correct = np.array(['2009-12-30', '2010-01-01', '2010-01-03'],
dtype='datetime64')
assert np.array_equal(result, correct)
def test_365_day_with_list(self):
result = climapy.dt_convert_to_datetime64(
[3648, 3650, 3652],
units='days since 1-1-1 00:00:00',
calendar='365_day')
correct = np.array(['0010-12-30', '0011-01-01', '0011-01-03'],
dtype='datetime64')
assert np.array_equal(result, correct)
def test_gregorian_with_int(self):
result = climapy.dt_convert_to_datetime64(
365 * 10 + 2,
units='days since 1-1-1 00:00:00',
calendar='gregorian')
correct = np.datetime64(
'0011-01-01T00:00:00') # two leap years in period
assert result == correct
def test_min_year(self):
result = climapy.dt_convert_to_datetime64(
[3648, 3650, 3652],
units='days since 1-1-1 00:00:00',
calendar='365_day',
min_year=1701)
correct = np.array(['1710-12-30', '1711-01-01', '1711-01-03'],
dtype='datetime64')
assert np.array_equal(result, correct)
def test_365_day_with_int(self):
result = climapy.dt_convert_to_datetime64(
365 * 10, units='days since 1-1-1 00:00:00', calendar='365_day')
correct = np.datetime64('0011-01-01')
assert result == correct
def test_invalid_min_year(self):
with pytest.raises(ValueError):
climapy.dt_convert_to_datetime64(1,
min_year=1971.) # float not int
def test_invalid_data_two(self):
with pytest.raises(ValueError):
climapy.dt_convert_to_datetime64(-1)
def test_invalid_data_one(self):
with pytest.raises(ValueError):
climapy.dt_convert_to_datetime64('string')
def test_invalid_units_three(self):
with pytest.raises(ValueError):
climapy.dt_convert_to_datetime64(1, units='days since the start')
def test_invalid_units_two(self):
with pytest.raises(ValueError):
climapy.dt_convert_to_datetime64(1, units='eons since 1-1-1 0:0:0')
def test_invalid_units_one(self):
with pytest.raises(ValueError):
climapy.dt_convert_to_datetime64(1, units='my_calendar')
