from __future__ import annotations import datetime from typing import List, Union from dateutil.relativedelta import relativedelta from .core import AllFrequencies, TimeSeriesCore, _parse_date, _preprocess_match_options def create_date_series( start_date: datetime.datetime, end_date: datetime.datetime, frequency: str, eomonth: bool = False ) -> List[datetime.datetime]: """Creates a date series using a frequency""" frequency = getattr(AllFrequencies, frequency) if eomonth and frequency.days < AllFrequencies.M.days: raise ValueError(f"eomonth cannot be set to True if frequency is higher than {AllFrequencies.M.name}") datediff = (end_date - start_date).days / frequency.days + 1 dates = [] for i in range(0, int(datediff)): diff = {frequency.freq_type: frequency.value * i} date = start_date + relativedelta(**diff) if eomonth: if date.month == 12: date = date.replace(day=31) else: date = date.replace(day=1).replace(month=date.month+1) - relativedelta(days=1) if date <= end_date: dates.append(date) return dates class TimeSeries(TimeSeriesCore): """Container for TimeSeries objects""" def info(self): """Summary info about the TimeSeries object""" total_dates = len(self.time_series.keys()) res_string = "First date: {}\nLast date: {}\nNumber of rows: {}" return res_string.format(self.start_date, self.end_date, total_dates) def ffill(self, inplace: bool = False, limit: int = None) -> Union[TimeSeries, None]: """Forward fill missing dates in the time series Parameters ---------- inplace : bool Modify the time-series data in place and return None. limit : int, optional Maximum number of periods to forward fill Returns ------- Returns a TimeSeries object if inplace is False, otherwise None """ eomonth = True if self.frequency.days >= AllFrequencies.M.days else False dates_to_fill = create_date_series(self.start_date, self.end_date, self.frequency.symbol, eomonth) new_ts = dict() for cur_date in dates_to_fill: try: cur_val = self.time_series[cur_date] except KeyError: pass new_ts.update({cur_date: cur_val}) if inplace: self.time_series = new_ts return None return TimeSeries(new_ts, frequency=self.frequency.symbol) def bfill(self, inplace: bool = False, limit: int = None) -> Union[TimeSeries, None]: """Backward fill missing dates in the time series Parameters ---------- inplace : bool Modify the time-series data in place and return None. limit : int, optional Maximum number of periods to back fill Returns ------- Returns a TimeSeries object if inplace is False, otherwise None """ eomonth = True if self.frequency.days >= AllFrequencies.M.days else False dates_to_fill = create_date_series(self.start_date, self.end_date, self.frequency.symbol, eomonth) dates_to_fill.append(self.end_date) bfill_ts = dict() for cur_date in reversed(dates_to_fill): try: cur_val = self.time_series[cur_date] except KeyError: pass bfill_ts.update({cur_date: cur_val}) new_ts = {k: bfill_ts[k] for k in reversed(bfill_ts)} if inplace: self.time_series = new_ts return None return TimeSeries(new_ts, frequency=self.frequency.symbol) def calculate_returns( self, as_on: Union[str, datetime.datetime], as_on_match: str = "closest", prior_match: str = "closest", closest: str = "previous", compounding: bool = True, years: int = 1, date_format: str = None ) -> float: """Method to calculate returns for a certain time-period as on a particular date Parameters ---------- as_on : datetime.datetime The date as on which the return is to be calculated. as_on_match : str, optional The mode of matching the as_on_date. Refer closest. prior_match : str, optional The mode of matching the prior_date. Refer closest. closest : str, optional The mode of matching the closest date. Valid values are 'exact', 'previous', 'next' and next. compounding : bool, optional Whether the return should be compounded annually. years : int, optional number of years for which the returns should be calculated Returns ------- The float value of the returns. Raises ------ ValueError * If match mode for any of the dates is exact and the exact match is not found * If the arguments passsed for closest, as_on_match, and prior_match are invalid Example -------- >>> calculate_returns(datetime.date(2020, 1, 1), years=1) """ as_on = _parse_date(as_on, date_format) as_on_delta, prior_delta = _preprocess_match_options(as_on_match, prior_match, closest) while True: current = self.time_series.get(as_on, None) if current is not None: break elif not as_on_delta: raise ValueError("As on date not found") as_on += as_on_delta prev_date = as_on - relativedelta(years=years) while True: previous = self.time_series.get(prev_date, None) if previous is not None: break elif not prior_delta: raise ValueError("Previous date not found") prev_date += prior_delta returns = current / previous if compounding: returns = returns ** (1 / years) return returns - 1 def calculate_rolling_returns( self, from_date: Union[datetime.date, str], to_date: Union[datetime.date, str], frequency: str = None, as_on_match: str = "closest", prior_match: str = "closest", closest: str = "previous", compounding: bool = True, years: int = 1, date_format: str = None ) -> List[tuple]: """Calculates the rolling return""" from_date = _parse_date(from_date, date_format) to_date = _parse_date(to_date, date_format) if frequency is None: frequency = self.frequency else: try: frequency = getattr(AllFrequencies, frequency) except AttributeError: raise ValueError(f"Invalid argument for frequency {frequency}") dates = create_date_series(from_date, to_date, frequency.symbol) if frequency == AllFrequencies.D: dates = [i for i in dates if i in self.time_series] rolling_returns = [] for i in dates: returns = self.calculate_returns( as_on=i, compounding=compounding, years=years, as_on_match=as_on_match, prior_match=prior_match, closest=closest, ) rolling_returns.append((i, returns)) rolling_returns.sort() return rolling_returns if __name__ == "__main__": date_series = [ datetime.datetime(2020, 1, 1), datetime.datetime(2020, 1, 2), datetime.datetime(2020, 1, 3), datetime.datetime(2020, 1, 4), datetime.datetime(2020, 1, 7), datetime.datetime(2020, 1, 8), datetime.datetime(2020, 1, 9), datetime.datetime(2020, 1, 10), datetime.datetime(2020, 1, 12), ]