def to_datetime(arg, errors='ignore', dayfirst=False):
"""
Convert argument to datetime
Parameters
----------
arg : string, datetime, array of strings (with possible NAs)
errors : {'ignore', 'raise'}, default 'ignore'
Errors are ignored by default (values left untouched)
Returns
-------
ret : datetime if parsing succeeded
"""
from pandas.core.series import Series
from pandas.tseries.index import DatetimeIndex
if arg is None:
return arg
elif isinstance(arg, datetime):
return arg
elif isinstance(arg, Series):
values = lib.string_to_datetime(com._ensure_object(arg.values),
raise_=errors == 'raise',
dayfirst=dayfirst)
return Series(values, index=arg.index, name=arg.name)
elif isinstance(arg, (np.ndarray, list)):
if isinstance(arg, list):
arg = np.array(arg, dtype='O')
result = lib.string_to_datetime(com._ensure_object(arg),
raise_=errors == 'raise',
dayfirst=dayfirst)
if com.is_datetime64_dtype(result):
result = DatetimeIndex(result)
return result
try:
if not arg:
return arg
return _dtparser.parse(arg, dayfirst=dayfirst)
except Exception:
if errors == 'raise':
raise
return arg
def test_string_na_nat_conversion(self):
# GH #999, #858
from dateutil.parser import parse
from pandas.core.datetools import to_datetime
strings = np.array(['1/1/2000', '1/2/2000', np.nan,
'1/4/2000, 12:34:56'], dtype=object)
expected = np.empty(4, dtype='M8')
for i, val in enumerate(strings):
if com.isnull(val):
expected[i] = NaT
else:
expected[i] = parse(val)
result = lib.string_to_datetime(strings)
assert_almost_equal(result, expected)
result2 = to_datetime(strings)
assert_almost_equal(result, result2)
malformed = np.array(['1/100/2000', np.nan], dtype=object)
result = to_datetime(malformed)
assert_almost_equal(result, malformed)
self.assertRaises(ValueError, to_datetime, malformed,
errors='raise')
idx = ['a', 'b', 'c', 'd', 'e']
series = Series(['1/1/2000', np.nan, '1/3/2000', np.nan,
'1/5/2000'], index=idx, name='foo')
dseries = Series([to_datetime('1/1/2000'), np.nan,
to_datetime('1/3/2000'), np.nan,
to_datetime('1/5/2000')], index=idx, name='foo')
result = to_datetime(series)
dresult = to_datetime(dseries)
expected = Series(np.empty(5, dtype='M8[us]'), index=idx)
for i in range(5):
x = series[i]
if isnull(x):
expected[i] = NaT
else:
expected[i] = to_datetime(x)
assert_series_equal(result, expected)
self.assertEquals(result.name, 'foo')
assert_series_equal(dresult, expected)
self.assertEquals(dresult.name, 'foo')
def test_string_na_nat_conversion(self):
# GH #999, #858
from dateutil.parser import parse
strings = np.array(["1/1/2000", "1/2/2000", np.nan, "1/4/2000, 12:34:56"], dtype=object)
expected = np.empty(4, dtype="M8")
for i, val in enumerate(strings):
if com.isnull(val):
expected[i] = NaT
else:
expected[i] = parse(val)
result = lib.string_to_datetime(strings)
assert_almost_equal(result, expected)
result2 = to_datetime(strings)
assert_almost_equal(result, result2)
malformed = np.array(["1/100/2000", np.nan], dtype=object)
result = to_datetime(malformed)
assert_almost_equal(result, malformed)
self.assertRaises(ValueError, to_datetime, malformed, errors="raise")
idx = ["a", "b", "c", "d", "e"]
series = Series(["1/1/2000", np.nan, "1/3/2000", np.nan, "1/5/2000"], index=idx, name="foo")
dseries = Series(
[to_datetime("1/1/2000"), np.nan, to_datetime("1/3/2000"), np.nan, to_datetime("1/5/2000")],
index=idx,
name="foo",
)
result = to_datetime(series)
dresult = to_datetime(dseries)
expected = Series(np.empty(5, dtype="M8[us]"), index=idx)
for i in range(5):
x = series[i]
if isnull(x):
expected[i] = NaT
else:
expected[i] = to_datetime(x)
assert_series_equal(result, expected)
self.assertEquals(result.name, "foo")
assert_series_equal(dresult, expected)
self.assertEquals(dresult.name, "foo")
