LSR/env/lib/python3.6/site-packages/pandas/tseries/frequencies.py

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2020-06-04 17:24:47 +02:00
from datetime import timedelta
import re
from typing import Dict, Optional
import warnings
import numpy as np
from pytz import AmbiguousTimeError
from pandas._libs.algos import unique_deltas
from pandas._libs.tslibs import Timedelta, Timestamp
from pandas._libs.tslibs.ccalendar import MONTH_ALIASES, int_to_weekday
from pandas._libs.tslibs.fields import build_field_sarray
import pandas._libs.tslibs.frequencies as libfreqs
from pandas._libs.tslibs.offsets import _offset_to_period_map
import pandas._libs.tslibs.resolution as libresolution
from pandas._libs.tslibs.resolution import Resolution
from pandas._libs.tslibs.timezones import UTC
from pandas._libs.tslibs.tzconversion import tz_convert
from pandas.util._decorators import cache_readonly
from pandas.core.dtypes.common import (
is_datetime64_dtype,
is_period_arraylike,
is_timedelta64_dtype,
)
from pandas.core.dtypes.generic import ABCSeries
from pandas.core.algorithms import unique
from pandas.tseries.offsets import (
DateOffset,
Day,
Hour,
Micro,
Milli,
Minute,
Nano,
Second,
prefix_mapping,
)
_ONE_MICRO = 1000
_ONE_MILLI = _ONE_MICRO * 1000
_ONE_SECOND = _ONE_MILLI * 1000
_ONE_MINUTE = 60 * _ONE_SECOND
_ONE_HOUR = 60 * _ONE_MINUTE
_ONE_DAY = 24 * _ONE_HOUR
# ---------------------------------------------------------------------
# Offset names ("time rules") and related functions
#: cache of previously seen offsets
_offset_map: Dict[str, DateOffset] = {}
def get_period_alias(offset_str: str) -> Optional[str]:
"""
Alias to closest period strings BQ->Q etc.
"""
return _offset_to_period_map.get(offset_str, None)
_name_to_offset_map = {
"days": Day(1),
"hours": Hour(1),
"minutes": Minute(1),
"seconds": Second(1),
"milliseconds": Milli(1),
"microseconds": Micro(1),
"nanoseconds": Nano(1),
}
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(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, 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:
raise ValueError(libfreqs.INVALID_FREQ_ERR_MSG.format(freq))
else:
delta = None
stride_sign = None
try:
splitted = re.split(libfreqs.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 = 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):
raise ValueError(libfreqs.INVALID_FREQ_ERR_MSG.format(freq))
if delta is None:
raise ValueError(libfreqs.INVALID_FREQ_ERR_MSG.format(freq))
return delta
def get_offset(name: str) -> DateOffset:
"""
Return DateOffset object associated with rule name.
.. deprecated:: 1.0.0
Examples
--------
get_offset('EOM') --> BMonthEnd(1)
"""
warnings.warn(
"get_offset is deprecated and will be removed in a future version, "
"use to_offset instead",
FutureWarning,
stacklevel=2,
)
return _get_offset(name)
def _get_offset(name: str) -> DateOffset:
"""
Return DateOffset object associated with rule name.
Examples
--------
_get_offset('EOM') --> BMonthEnd(1)
"""
if name not in libfreqs._dont_uppercase:
name = name.upper()
name = libfreqs._lite_rule_alias.get(name, name)
name = libfreqs._lite_rule_alias.get(name.lower(), name)
else:
name = libfreqs._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(libfreqs.INVALID_FREQ_ERR_MSG.format(name))
# cache
_offset_map[name] = offset
return _offset_map[name]
# ---------------------------------------------------------------------
# Period codes
def infer_freq(index, warn: bool = True) -> Optional[str]:
"""
Infer the most likely frequency given the input index. If the frequency is
uncertain, a warning will be printed.
Parameters
----------
index : DatetimeIndex or TimedeltaIndex
If passed a Series will use the values of the series (NOT THE INDEX).
warn : bool, default True
Returns
-------
str or None
None if no discernible frequency
TypeError if the index is not datetime-like
ValueError if there are less than three values.
"""
import pandas as pd
if isinstance(index, ABCSeries):
values = index._values
if not (
is_datetime64_dtype(values)
or is_timedelta64_dtype(values)
or values.dtype == object
):
raise TypeError(
"cannot infer freq from a non-convertible dtype "
f"on a Series of {index.dtype}"
)
index = values
inferer: _FrequencyInferer
if is_period_arraylike(index):
raise TypeError(
"PeriodIndex given. Check the `freq` attribute "
"instead of using infer_freq."
)
elif is_timedelta64_dtype(index):
# Allow TimedeltaIndex and TimedeltaArray
inferer = _TimedeltaFrequencyInferer(index, warn=warn)
return inferer.get_freq()
if isinstance(index, pd.Index) and not isinstance(index, pd.DatetimeIndex):
if isinstance(index, (pd.Int64Index, pd.Float64Index)):
raise TypeError(
f"cannot infer freq from a non-convertible index type {type(index)}"
)
index = index.values
if not isinstance(index, pd.DatetimeIndex):
try:
index = pd.DatetimeIndex(index)
except AmbiguousTimeError:
index = pd.DatetimeIndex(index.asi8)
inferer = _FrequencyInferer(index, warn=warn)
return inferer.get_freq()
class _FrequencyInferer:
"""
Not sure if I can avoid the state machine here
"""
def __init__(self, index, warn: bool = True):
self.index = index
self.values = index.asi8
# This moves the values, which are implicitly in UTC, to the
# the timezone so they are in local time
if hasattr(index, "tz"):
if index.tz is not None:
self.values = tz_convert(self.values, UTC, index.tz)
self.warn = warn
if len(index) < 3:
raise ValueError("Need at least 3 dates to infer frequency")
self.is_monotonic = (
self.index._is_monotonic_increasing or self.index._is_monotonic_decreasing
)
@cache_readonly
def deltas(self):
return unique_deltas(self.values)
@cache_readonly
def deltas_asi8(self):
return unique_deltas(self.index.asi8)
@cache_readonly
def is_unique(self) -> bool:
return len(self.deltas) == 1
@cache_readonly
def is_unique_asi8(self):
return len(self.deltas_asi8) == 1
def get_freq(self) -> Optional[str]:
"""
Find the appropriate frequency string to describe the inferred
frequency of self.values
Returns
-------
str or None
"""
if not self.is_monotonic or not self.index._is_unique:
return None
delta = self.deltas[0]
if _is_multiple(delta, _ONE_DAY):
return self._infer_daily_rule()
# Business hourly, maybe. 17: one day / 65: one weekend
if self.hour_deltas in ([1, 17], [1, 65], [1, 17, 65]):
return "BH"
# Possibly intraday frequency. Here we use the
# original .asi8 values as the modified values
# will not work around DST transitions. See #8772
elif not self.is_unique_asi8:
return None
delta = self.deltas_asi8[0]
if _is_multiple(delta, _ONE_HOUR):
# Hours
return _maybe_add_count("H", delta / _ONE_HOUR)
elif _is_multiple(delta, _ONE_MINUTE):
# Minutes
return _maybe_add_count("T", delta / _ONE_MINUTE)
elif _is_multiple(delta, _ONE_SECOND):
# Seconds
return _maybe_add_count("S", delta / _ONE_SECOND)
elif _is_multiple(delta, _ONE_MILLI):
# Milliseconds
return _maybe_add_count("L", delta / _ONE_MILLI)
elif _is_multiple(delta, _ONE_MICRO):
# Microseconds
return _maybe_add_count("U", delta / _ONE_MICRO)
else:
# Nanoseconds
return _maybe_add_count("N", delta)
@cache_readonly
def day_deltas(self):
return [x / _ONE_DAY for x in self.deltas]
@cache_readonly
def hour_deltas(self):
return [x / _ONE_HOUR for x in self.deltas]
@cache_readonly
def fields(self):
return build_field_sarray(self.values)
@cache_readonly
def rep_stamp(self):
return Timestamp(self.values[0])
def month_position_check(self):
return libresolution.month_position_check(self.fields, self.index.dayofweek)
@cache_readonly
def mdiffs(self):
nmonths = self.fields["Y"] * 12 + self.fields["M"]
return unique_deltas(nmonths.astype("i8"))
@cache_readonly
def ydiffs(self):
return unique_deltas(self.fields["Y"].astype("i8"))
def _infer_daily_rule(self) -> Optional[str]:
annual_rule = self._get_annual_rule()
if annual_rule:
nyears = self.ydiffs[0]
month = MONTH_ALIASES[self.rep_stamp.month]
alias = f"{annual_rule}-{month}"
return _maybe_add_count(alias, nyears)
quarterly_rule = self._get_quarterly_rule()
if quarterly_rule:
nquarters = self.mdiffs[0] / 3
mod_dict = {0: 12, 2: 11, 1: 10}
month = MONTH_ALIASES[mod_dict[self.rep_stamp.month % 3]]
alias = f"{quarterly_rule}-{month}"
return _maybe_add_count(alias, nquarters)
monthly_rule = self._get_monthly_rule()
if monthly_rule:
return _maybe_add_count(monthly_rule, self.mdiffs[0])
if self.is_unique:
days = self.deltas[0] / _ONE_DAY
if days % 7 == 0:
# Weekly
day = int_to_weekday[self.rep_stamp.weekday()]
return _maybe_add_count(f"W-{day}", days / 7)
else:
return _maybe_add_count("D", days)
if self._is_business_daily():
return "B"
wom_rule = self._get_wom_rule()
if wom_rule:
return wom_rule
return None
def _get_annual_rule(self) -> Optional[str]:
if len(self.ydiffs) > 1:
return None
if len(unique(self.fields["M"])) > 1:
return None
pos_check = self.month_position_check()
return {"cs": "AS", "bs": "BAS", "ce": "A", "be": "BA"}.get(pos_check)
def _get_quarterly_rule(self) -> Optional[str]:
if len(self.mdiffs) > 1:
return None
if not self.mdiffs[0] % 3 == 0:
return None
pos_check = self.month_position_check()
return {"cs": "QS", "bs": "BQS", "ce": "Q", "be": "BQ"}.get(pos_check)
def _get_monthly_rule(self) -> Optional[str]:
if len(self.mdiffs) > 1:
return None
pos_check = self.month_position_check()
return {"cs": "MS", "bs": "BMS", "ce": "M", "be": "BM"}.get(pos_check)
def _is_business_daily(self) -> bool:
# quick check: cannot be business daily
if self.day_deltas != [1, 3]:
return False
# probably business daily, but need to confirm
first_weekday = self.index[0].weekday()
shifts = np.diff(self.index.asi8)
shifts = np.floor_divide(shifts, _ONE_DAY)
weekdays = np.mod(first_weekday + np.cumsum(shifts), 7)
return np.all(
((weekdays == 0) & (shifts == 3))
| ((weekdays > 0) & (weekdays <= 4) & (shifts == 1))
)
def _get_wom_rule(self) -> Optional[str]:
# wdiffs = unique(np.diff(self.index.week))
# We also need -47, -49, -48 to catch index spanning year boundary
# if not lib.ismember(wdiffs, set([4, 5, -47, -49, -48])).all():
# return None
weekdays = unique(self.index.weekday)
if len(weekdays) > 1:
return None
week_of_months = unique((self.index.day - 1) // 7)
# Only attempt to infer up to WOM-4. See #9425
week_of_months = week_of_months[week_of_months < 4]
if len(week_of_months) == 0 or len(week_of_months) > 1:
return None
# get which week
week = week_of_months[0] + 1
wd = int_to_weekday[weekdays[0]]
return f"WOM-{week}{wd}"
class _TimedeltaFrequencyInferer(_FrequencyInferer):
def _infer_daily_rule(self):
if self.is_unique:
days = self.deltas[0] / _ONE_DAY
if days % 7 == 0:
# Weekly
wd = int_to_weekday[self.rep_stamp.weekday()]
alias = f"W-{wd}"
return _maybe_add_count(alias, days / 7)
else:
return _maybe_add_count("D", days)
def _is_multiple(us, mult: int) -> bool:
return us % mult == 0
def _maybe_add_count(base: str, count: float) -> str:
if count != 1:
assert count == int(count)
count = int(count)
return f"{count}{base}"
else:
return base