def to_offset(freq):
"""
Return DateOffset object from string or tuple representation
or datetime.timedelta object
Parameters
----------
freq : str, tuple, datetime.timedelta, DateOffset or None
Returns
-------
delta : DateOffset
None if freq is None
Raises
------
ValueError
If freq is an invalid frequency
See Also
--------
pandas.DateOffset
Examples
--------
>>> to_offset('5min')
<5 * Minutes>
>>> to_offset('1D1H')
<25 * Hours>
>>> to_offset(('W', 2))
<2 * Weeks: weekday=6>
>>> to_offset((2, 'B'))
<2 * BusinessDays>
>>> to_offset(datetime.timedelta(days=1))
<Day>
>>> to_offset(Hour())
<Hour>
"""
if freq is None:
return None
if isinstance(freq, DateOffset):
return freq
if isinstance(freq, tuple):
name = freq[0]
stride = freq[1]
if isinstance(stride, compat.string_types):
name, stride = stride, name
name, _ = _base_and_stride(name)
delta = get_offset(name) * stride
elif isinstance(freq, timedelta):
delta = None
freq = Timedelta(freq)
try:
for name in freq.components._fields:
offset = _name_to_offset_map[name]
stride = getattr(freq.components, name)
if stride != 0:
offset = stride * offset
if delta is None:
delta = offset
else:
delta = delta + offset
except Exception:
raise ValueError(_INVALID_FREQ_ERROR.format(freq))
else:
delta = None
stride_sign = None
try:
splitted = re.split(opattern, freq)
if splitted[-1] != '' and not splitted[-1].isspace():
# the last element must be blank
raise ValueError('last element must be blank')
for sep, stride, name in zip(splitted[0::4], splitted[1::4],
splitted[2::4]):
if sep != '' and not sep.isspace():
raise ValueError('separator must be spaces')
prefix = _lite_rule_alias.get(name) or name
if stride_sign is None:
stride_sign = -1 if stride.startswith('-') else 1
if not stride:
stride = 1
if prefix in Resolution._reso_str_bump_map.keys():
stride, name = Resolution.get_stride_from_decimal(
float(stride), prefix
)
stride = int(stride)
offset = get_offset(name)
offset = offset * int(np.fabs(stride) * stride_sign)
if delta is None:
delta = offset
else:
delta = delta + offset
except Exception:
raise ValueError(_INVALID_FREQ_ERROR.format(freq))
if delta is None:
raise ValueError(_INVALID_FREQ_ERROR.format(freq))
return delta
def get_base_alias(freqstr):
"""
Returns the base frequency alias, e.g., '5D' -> 'D'
"""
return _base_and_stride(freqstr)[0]
def to_offset(freq) -> Optional[DateOffset]:
"""
Return DateOffset object from string or tuple representation
or datetime.timedelta object.
Parameters
----------
freq : str, tuple, datetime.timedelta, DateOffset or None
Returns
-------
DateOffset
None if freq is None.
Raises
------
ValueError
If freq is an invalid frequency
See Also
--------
DateOffset
Examples
--------
>>> to_offset("5min")
<5 * Minutes>
>>> to_offset("1D1H")
<25 * Hours>
>>> to_offset(("W", 2))
<2 * Weeks: weekday=6>
>>> to_offset((2, "B"))
<2 * BusinessDays>
>>> to_offset(pd.Timedelta(days=1))
<Day>
>>> to_offset(Hour())
<Hour>
"""
if freq is None:
return None
if isinstance(freq, DateOffset):
return freq
if isinstance(freq, tuple):
name = freq[0]
stride = freq[1]
if isinstance(stride, str):
name, stride = stride, name
name, _ = libfreqs._base_and_stride(name)
delta = _get_offset(name) * stride
elif isinstance(freq, timedelta):
delta = None
freq = Timedelta(freq)
try:
for name in freq.components._fields:
offset = _name_to_offset_map[name]
stride = getattr(freq.components, name)
if stride != 0:
offset = stride * offset
if delta is None:
delta = offset
else:
delta = delta + offset
except ValueError as err:
raise ValueError(libfreqs.INVALID_FREQ_ERR_MSG.format(freq)) from err
else:
delta = None
stride_sign = None
try:
split = re.split(libfreqs.opattern, freq)
if split[-1] != "" and not split[-1].isspace():
# the last element must be blank
raise ValueError("last element must be blank")
for sep, stride, name in zip(split[0::4], split[1::4], split[2::4]):
if sep != "" and not sep.isspace():
raise ValueError("separator must be spaces")
prefix = libfreqs._lite_rule_alias.get(name) or name
if stride_sign is None:
stride_sign = -1 if stride.startswith("-") else 1
if not stride:
stride = 1
if prefix in Resolution._reso_str_bump_map.keys():
stride, name = Resolution.get_stride_from_decimal(
float(stride), prefix
)
stride = int(stride)
offset = _get_offset(name)
offset = offset * int(np.fabs(stride) * stride_sign)
if delta is None:
delta = offset
else:
delta = delta + offset
except (ValueError, TypeError) as err:
raise ValueError(libfreqs.INVALID_FREQ_ERR_MSG.format(freq)) from err
if delta is None:
raise ValueError(libfreqs.INVALID_FREQ_ERR_MSG.format(freq))
return delta
