def get_offset(name): """ Return DateOffset object associated with rule name Examples -------- get_offset('EOM') --> BMonthEnd(1) """ if name not in _dont_uppercase: name = name.upper() name = _lite_rule_alias.get(name, name) name = _lite_rule_alias.get(name.lower(), name) else: name = _lite_rule_alias.get(name, name) if name not in _offset_map: try: split = name.split('-') klass = prefix_mapping[split[0]] # handles case where there's no suffix (and will TypeError if too # many '-') offset = klass._from_name(*split[1:]) except (ValueError, TypeError, KeyError): # bad prefix or suffix raise ValueError(_INVALID_FREQ_ERROR.format(name)) # cache _offset_map[name] = offset # do not return cache because it's mutable return _offset_map[name].copy()
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