Class YearBegin

xarray/coding/cftime_offsets.py:562–584

class YearBegin(YearOffset):
    _freq = "YS"
    _day_option = "start"
    _default_month = 1

    def onOffset(self, date) -> bool:
        """Check if the given date is in the set of possible dates created
        using a length-one version of this offset class."""
        return date.day == 1 and date.month == self.month

    def rollforward(self, date):
        """Roll date forward to nearest start of year"""
        if self.onOffset(date):
            return date
        else:
            return date + YearBegin(month=self.month)

    def rollback(self, date):
        """Roll date backward to nearest start of year"""
        if self.onOffset(date):
            return date
        else:
            return date - YearBegin(month=self.month)


class YearEnd(YearOffset):