Python datetime.replace() Examples

The following are 28 code examples for showing how to use datetime.replace(). These examples are extracted from open source projects. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example.

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Example 1
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 6 votes vote down vote up
def strftime(self, dt, fmt=None):
        """
        Refer to documentation for :meth:`datetime.datetime.strftime`

        *fmt* is a :meth:`datetime.datetime.strftime` format string.

        Warning: For years before 1900, depending upon the current
        locale it is possible that the year displayed with %x might
        be incorrect. For years before 100, %y and %Y will yield
        zero-padded strings.
        """
        if fmt is None:
            fmt = self.fmt
        fmt = self.illegal_s.sub(r"\1", fmt)
        fmt = fmt.replace("%s", "s")
        if dt.year >= 1900:
            # Note: in python 3.3 this is okay for years >= 1000,
            # refer to http://bugs.python.org/issue1777412
            return cbook.unicode_safe(dt.strftime(fmt))

        return self.strftime_pre_1900(dt, fmt) 
Example 2
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 6 votes vote down vote up
def __init__(self, base=1, month=1, day=1, tz=None):
        """
        Mark years that are multiple of base on a given month and day
        (default jan 1).
        """
        DateLocator.__init__(self, tz)
        self.base = ticker._Edge_integer(base, 0)
        self.replaced = {'month':  month,
                         'day':    day,
                         'hour':   0,
                         'minute': 0,
                         'second': 0,
                         }
        if not hasattr(tz, 'localize'):
            # if tz is pytz, we need to do this w/ the localize fcn,
            # otherwise datetime.replace works fine...
            self.replaced['tzinfo'] = tz 
Example 3
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 6 votes vote down vote up
def tick_values(self, vmin, vmax):
        ymin = self.base.le(vmin.year) * self.base.step
        ymax = self.base.ge(vmax.year) * self.base.step

        vmin = vmin.replace(year=ymin, **self.replaced)
        if hasattr(self.tz, 'localize'):
            # look after pytz
            if not vmin.tzinfo:
                vmin = self.tz.localize(vmin, is_dst=True)

        ticks = [vmin]

        while True:
            dt = ticks[-1]
            if dt.year >= ymax:
                return date2num(ticks)
            year = dt.year + self.base.step
            dt = dt.replace(year=year, **self.replaced)
            if hasattr(self.tz, 'localize'):
                # look after pytz
                if not dt.tzinfo:
                    dt = self.tz.localize(dt, is_dst=True)

            ticks.append(dt) 
Example 4
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 6 votes vote down vote up
def autoscale(self):
        """
        Set the view limits to include the data range.
        """
        dmin, dmax = self.datalim_to_dt()

        ymin = self.base.le(dmin.year)
        ymax = self.base.ge(dmax.year)
        vmin = dmin.replace(year=ymin, **self.replaced)
        vmin = vmin.astimezone(self.tz)
        vmax = dmax.replace(year=ymax, **self.replaced)
        vmax = vmax.astimezone(self.tz)

        vmin = date2num(vmin)
        vmax = date2num(vmax)
        return self.nonsingular(vmin, vmax) 
Example 5
Project: Ocean-Data-Map-Project   Author: DFO-Ocean-Navigator   File: utils.py    License: GNU General Public License v3.0 6 votes vote down vote up
def datetime_to_timestamp(datetime: datetime.datetime, time_units: str):
    """Converts a given datetime object and time units string
    into a netcdf timestamp integer with UTC encoding.

    Arguments:
        datetime {datetime.datetime} -- some datetime object
        time_units {str} -- time units (e.g. 'seconds since 1950-01-01 00:00:00')

    Returns:
        [int] -- timestamp integer
    """

    t = cftime.utime(time_units)

    datetime = datetime.replace(tzinfo=pytz.UTC)
    return t.date2num(datetime) 
Example 6
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 6 votes vote down vote up
def strftime(self, dt, fmt=None):
        """
        Refer to documentation for :meth:`datetime.datetime.strftime`

        *fmt* is a :meth:`datetime.datetime.strftime` format string.

        Warning: For years before 1900, depending upon the current
        locale it is possible that the year displayed with %x might
        be incorrect. For years before 100, %y and %Y will yield
        zero-padded strings.
        """
        if fmt is None:
            fmt = self.fmt
        fmt = self.illegal_s.sub(r"\1", fmt)
        fmt = fmt.replace("%s", "s")
        if dt.year >= 1900:
            # Note: in python 3.3 this is okay for years >= 1000,
            # refer to http://bugs.python.org/issue1777412
            return cbook.unicode_safe(dt.strftime(fmt))

        return self.strftime_pre_1900(dt, fmt) 
Example 7
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 6 votes vote down vote up
def __init__(self, base=1, month=1, day=1, tz=None):
        """
        Mark years that are multiple of base on a given month and day
        (default jan 1).
        """
        DateLocator.__init__(self, tz)
        self.base = ticker._Edge_integer(base, 0)
        self.replaced = {'month':  month,
                         'day':    day,
                         'hour':   0,
                         'minute': 0,
                         'second': 0,
                         }
        if not hasattr(tz, 'localize'):
            # if tz is pytz, we need to do this w/ the localize fcn,
            # otherwise datetime.replace works fine...
            self.replaced['tzinfo'] = tz 
Example 8
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 6 votes vote down vote up
def tick_values(self, vmin, vmax):
        ymin = self.base.le(vmin.year) * self.base.step
        ymax = self.base.ge(vmax.year) * self.base.step

        vmin = vmin.replace(year=ymin, **self.replaced)
        if hasattr(self.tz, 'localize'):
            # look after pytz
            if not vmin.tzinfo:
                vmin = self.tz.localize(vmin, is_dst=True)

        ticks = [vmin]

        while True:
            dt = ticks[-1]
            if dt.year >= ymax:
                return date2num(ticks)
            year = dt.year + self.base.step
            dt = dt.replace(year=year, **self.replaced)
            if hasattr(self.tz, 'localize'):
                # look after pytz
                if not dt.tzinfo:
                    dt = self.tz.localize(dt, is_dst=True)

            ticks.append(dt) 
Example 9
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 6 votes vote down vote up
def autoscale(self):
        """
        Set the view limits to include the data range.
        """
        dmin, dmax = self.datalim_to_dt()

        ymin = self.base.le(dmin.year)
        ymax = self.base.ge(dmax.year)
        vmin = dmin.replace(year=ymin, **self.replaced)
        vmin = vmin.astimezone(self.tz)
        vmax = dmax.replace(year=ymax, **self.replaced)
        vmax = vmax.astimezone(self.tz)

        vmin = date2num(vmin)
        vmax = date2num(vmax)
        return self.nonsingular(vmin, vmax) 
Example 10
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 6 votes vote down vote up
def strftime(self, dt, fmt=None):
        """
        Refer to documentation for :meth:`datetime.datetime.strftime`

        *fmt* is a :meth:`datetime.datetime.strftime` format string.

        Warning: For years before 1900, depending upon the current
        locale it is possible that the year displayed with %x might
        be incorrect. For years before 100, %y and %Y will yield
        zero-padded strings.
        """
        if fmt is None:
            fmt = self.fmt
        fmt = self.illegal_s.sub(r"\1", fmt)
        fmt = fmt.replace("%s", "s")
        if dt.year >= 1900:
            # Note: in python 3.3 this is okay for years >= 1000,
            # refer to http://bugs.python.org/issue1777412
            return cbook.unicode_safe(dt.strftime(fmt))

        return self.strftime_pre_1900(dt, fmt) 
Example 11
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 6 votes vote down vote up
def __init__(self, base=1, month=1, day=1, tz=None):
        """
        Mark years that are multiple of base on a given month and day
        (default jan 1).
        """
        DateLocator.__init__(self, tz)
        self.base = ticker._Edge_integer(base, 0)
        self.replaced = {'month':  month,
                         'day':    day,
                         'hour':   0,
                         'minute': 0,
                         'second': 0,
                         }
        if not hasattr(tz, 'localize'):
            # if tz is pytz, we need to do this w/ the localize fcn,
            # otherwise datetime.replace works fine...
            self.replaced['tzinfo'] = tz 
Example 12
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 6 votes vote down vote up
def tick_values(self, vmin, vmax):
        ymin = self.base.le(vmin.year) * self.base.step
        ymax = self.base.ge(vmax.year) * self.base.step

        vmin = vmin.replace(year=ymin, **self.replaced)
        if hasattr(self.tz, 'localize'):
            # look after pytz
            if not vmin.tzinfo:
                vmin = self.tz.localize(vmin, is_dst=True)

        ticks = [vmin]

        while True:
            dt = ticks[-1]
            if dt.year >= ymax:
                return date2num(ticks)
            year = dt.year + self.base.step
            dt = dt.replace(year=year, **self.replaced)
            if hasattr(self.tz, 'localize'):
                # look after pytz
                if not dt.tzinfo:
                    dt = self.tz.localize(dt, is_dst=True)

            ticks.append(dt) 
Example 13
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 6 votes vote down vote up
def autoscale(self):
        """
        Set the view limits to include the data range.
        """
        dmin, dmax = self.datalim_to_dt()

        ymin = self.base.le(dmin.year)
        ymax = self.base.ge(dmax.year)
        vmin = dmin.replace(year=ymin, **self.replaced)
        vmin = vmin.astimezone(self.tz)
        vmax = dmax.replace(year=ymax, **self.replaced)
        vmax = vmax.astimezone(self.tz)

        vmin = date2num(vmin)
        vmax = date2num(vmax)
        return self.nonsingular(vmin, vmax) 
Example 14
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 5 votes vote down vote up
def _from_ordinalf(x, tz=None):
    """
    Convert Gregorian float of the date, preserving hours, minutes,
    seconds and microseconds.  Return value is a `.datetime`.

    The input date *x* is a float in ordinal days at UTC, and the output will
    be the specified `.datetime` object corresponding to that time in
    timezone *tz*, or if *tz* is ``None``, in the timezone specified in
    :rc:`timezone`.
    """
    if tz is None:
        tz = _get_rc_timezone()

    ix, remainder = divmod(x, 1)
    ix = int(ix)
    if ix < 1:
        raise ValueError('Cannot convert {} to a date.  This often happens if '
                         'non-datetime values are passed to an axis that '
                         'expects datetime objects.'.format(ix))
    dt = datetime.datetime.fromordinal(ix).replace(tzinfo=UTC)

    # Since the input date `x` float is unable to preserve microsecond
    # precision of time representation in non-antique years, the
    # resulting datetime is rounded to the nearest multiple of
    # `musec_prec`. A value of 20 is appropriate for current dates.
    musec_prec = 20
    remainder_musec = int(round(remainder * MUSECONDS_PER_DAY / musec_prec)
                          * musec_prec)

    # For people trying to plot with full microsecond precision, enable
    # an early-year workaround
    if x < 30 * 365:
        remainder_musec = int(round(remainder * MUSECONDS_PER_DAY))

    # add hours, minutes, seconds, microseconds
    dt += datetime.timedelta(microseconds=remainder_musec)

    return dt.astimezone(tz)


# a version of _from_ordinalf that can operate on numpy arrays 
Example 15
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 5 votes vote down vote up
def _update_rrule(self, **kwargs):
        tzinfo = self._base_tzinfo

        # rrule does not play nicely with time zones - especially pytz time
        # zones, it's best to use naive zones and attach timezones once the
        # datetimes are returned
        if 'dtstart' in kwargs:
            dtstart = kwargs['dtstart']
            if dtstart.tzinfo is not None:
                if tzinfo is None:
                    tzinfo = dtstart.tzinfo
                else:
                    dtstart = dtstart.astimezone(tzinfo)

                kwargs['dtstart'] = dtstart.replace(tzinfo=None)

        if 'until' in kwargs:
            until = kwargs['until']
            if until.tzinfo is not None:
                if tzinfo is not None:
                    until = until.astimezone(tzinfo)
                else:
                    raise ValueError('until cannot be aware if dtstart '
                                     'is naive and tzinfo is None')

                kwargs['until'] = until.replace(tzinfo=None)

        self._construct = kwargs.copy()
        self._tzinfo = tzinfo
        self._rrule = rrule(**self._construct) 
Example 16
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 5 votes vote down vote up
def _attach_tzinfo(self, dt, tzinfo):
        # pytz zones are attached by "localizing" the datetime
        if hasattr(tzinfo, 'localize'):
            return tzinfo.localize(dt, is_dst=True)

        return dt.replace(tzinfo=tzinfo) 
Example 17
Project: googleapps-message-recall   Author: google   File: i18n.py    License: Apache License 2.0 5 votes vote down vote up
def to_local_timezone(self, datetime):
        """Returns a datetime object converted to the local timezone.

        :param datetime:
            A ``datetime`` object.
        :returns:
            A ``datetime`` object normalized to a timezone.
        """
        if datetime.tzinfo is None:
            datetime = datetime.replace(tzinfo=pytz.UTC)

        return self.tzinfo.normalize(datetime.astimezone(self.tzinfo)) 
Example 18
Project: googleapps-message-recall   Author: google   File: i18n.py    License: Apache License 2.0 5 votes vote down vote up
def to_utc(self, datetime):
        """Returns a datetime object converted to UTC and without tzinfo.

        :param datetime:
            A ``datetime`` object.
        :returns:
            A naive ``datetime`` object (no timezone), converted to UTC.
        """
        if datetime.tzinfo is None:
            datetime = self.tzinfo.localize(datetime)

        return datetime.astimezone(pytz.UTC).replace(tzinfo=None) 
Example 19
Project: Ocean-Data-Map-Project   Author: DFO-Ocean-Navigator   File: utils.py    License: GNU General Public License v3.0 5 votes vote down vote up
def time_index_to_datetime(timestamps, time_units: str):

    if isinstance(timestamps, np.ndarray):
        timestamps = timestamps.tolist()

    if not isinstance(timestamps, list):
        timestamps = [timestamps]

    result = [cftime.num2date(timestamp, time_units).replace(tzinfo=pytz.UTC) for timestamp in timestamps]

    if isinstance(result[0], list):
        return list(itertools.chain(*result))

    return result 
Example 20
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 5 votes vote down vote up
def _from_ordinalf(x, tz=None):
    """
    Convert Gregorian float of the date, preserving hours, minutes,
    seconds and microseconds.  Return value is a `.datetime`.

    The input date *x* is a float in ordinal days at UTC, and the output will
    be the specified `.datetime` object corresponding to that time in
    timezone *tz*, or if *tz* is ``None``, in the timezone specified in
    :rc:`timezone`.
    """
    if tz is None:
        tz = _get_rc_timezone()

    ix, remainder = divmod(x, 1)
    ix = int(ix)
    if ix < 1:
        raise ValueError('Cannot convert {} to a date.  This often happens if '
                         'non-datetime values are passed to an axis that '
                         'expects datetime objects.'.format(ix))
    dt = datetime.datetime.fromordinal(ix).replace(tzinfo=UTC)

    # Since the input date `x` float is unable to preserve microsecond
    # precision of time representation in non-antique years, the
    # resulting datetime is rounded to the nearest multiple of
    # `musec_prec`. A value of 20 is appropriate for current dates.
    musec_prec = 20
    remainder_musec = int(round(remainder * MUSECONDS_PER_DAY / musec_prec)
                          * musec_prec)

    # For people trying to plot with full microsecond precision, enable
    # an early-year workaround
    if x < 30 * 365:
        remainder_musec = int(round(remainder * MUSECONDS_PER_DAY))

    # add hours, minutes, seconds, microseconds
    dt += datetime.timedelta(microseconds=remainder_musec)

    return dt.astimezone(tz)


# a version of _from_ordinalf that can operate on numpy arrays 
Example 21
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 5 votes vote down vote up
def _update_rrule(self, **kwargs):
        tzinfo = self._base_tzinfo

        # rrule does not play nicely with time zones - especially pytz time
        # zones, it's best to use naive zones and attach timezones once the
        # datetimes are returned
        if 'dtstart' in kwargs:
            dtstart = kwargs['dtstart']
            if dtstart.tzinfo is not None:
                if tzinfo is None:
                    tzinfo = dtstart.tzinfo
                else:
                    dtstart = dtstart.astimezone(tzinfo)

                kwargs['dtstart'] = dtstart.replace(tzinfo=None)

        if 'until' in kwargs:
            until = kwargs['until']
            if until.tzinfo is not None:
                if tzinfo is not None:
                    until = until.astimezone(tzinfo)
                else:
                    raise ValueError('until cannot be aware if dtstart '
                                     'is naive and tzinfo is None')

                kwargs['until'] = until.replace(tzinfo=None)

        self._construct = kwargs.copy()
        self._tzinfo = tzinfo
        self._rrule = rrule(**self._construct) 
Example 22
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 5 votes vote down vote up
def _attach_tzinfo(self, dt, tzinfo):
        # pytz zones are attached by "localizing" the datetime
        if hasattr(tzinfo, 'localize'):
            return tzinfo.localize(dt, is_dst=True)

        return dt.replace(tzinfo=tzinfo) 
Example 23
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 5 votes vote down vote up
def _from_ordinalf(x, tz=None):
    """
    Convert Gregorian float of the date, preserving hours, minutes,
    seconds and microseconds.  Return value is a `.datetime`.

    The input date *x* is a float in ordinal days at UTC, and the output will
    be the specified `.datetime` object corresponding to that time in
    timezone *tz*, or if *tz* is ``None``, in the timezone specified in
    :rc:`timezone`.
    """
    if tz is None:
        tz = _get_rc_timezone()

    ix, remainder = divmod(x, 1)
    ix = int(ix)
    if ix < 1:
        raise ValueError('Cannot convert {} to a date.  This often happens if '
                         'non-datetime values are passed to an axis that '
                         'expects datetime objects.'.format(ix))
    dt = datetime.datetime.fromordinal(ix).replace(tzinfo=UTC)

    # Since the input date `x` float is unable to preserve microsecond
    # precision of time representation in non-antique years, the
    # resulting datetime is rounded to the nearest multiple of
    # `musec_prec`. A value of 20 is appropriate for current dates.
    musec_prec = 20
    remainder_musec = int(round(remainder * MUSECONDS_PER_DAY / musec_prec)
                          * musec_prec)

    # For people trying to plot with full microsecond precision, enable
    # an early-year workaround
    if x < 30 * 365:
        remainder_musec = int(round(remainder * MUSECONDS_PER_DAY))

    # add hours, minutes, seconds, microseconds
    dt += datetime.timedelta(microseconds=remainder_musec)
    return dt.astimezone(tz)


# a version of _from_ordinalf that can operate on numpy arrays 
Example 24
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 5 votes vote down vote up
def _update_rrule(self, **kwargs):
        tzinfo = self._base_tzinfo

        # rrule does not play nicely with time zones - especially pytz time
        # zones, it's best to use naive zones and attach timezones once the
        # datetimes are returned
        if 'dtstart' in kwargs:
            dtstart = kwargs['dtstart']
            if dtstart.tzinfo is not None:
                if tzinfo is None:
                    tzinfo = dtstart.tzinfo
                else:
                    dtstart = dtstart.astimezone(tzinfo)

                kwargs['dtstart'] = dtstart.replace(tzinfo=None)

        if 'until' in kwargs:
            until = kwargs['until']
            if until.tzinfo is not None:
                if tzinfo is not None:
                    until = until.astimezone(tzinfo)
                else:
                    raise ValueError('until cannot be aware if dtstart '
                                     'is naive and tzinfo is None')

                kwargs['until'] = until.replace(tzinfo=None)

        self._construct = kwargs.copy()
        self._tzinfo = tzinfo
        self._rrule = rrule(**self._construct) 
Example 25
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 5 votes vote down vote up
def _attach_tzinfo(self, dt, tzinfo):
        # pytz zones are attached by "localizing" the datetime
        if hasattr(tzinfo, 'localize'):
            return tzinfo.localize(dt, is_dst=True)

        return dt.replace(tzinfo=tzinfo) 
Example 26
Project: python3_ios   Author: holzschu   File: dates.py    License: BSD 3-Clause "New" or "Revised" License 4 votes vote down vote up
def strftime_pre_1900(self, dt, fmt=None):
        """Call time.strftime for years before 1900 by rolling
        forward a multiple of 28 years.

        *fmt* is a :func:`strftime` format string.

        Dalke: I hope I did this math right.  Every 28 years the
        calendar repeats, except through century leap years excepting
        the 400 year leap years.  But only if you're using the Gregorian
        calendar.
        """
        if fmt is None:
            fmt = self.fmt

        # Since python's time module's strftime implementation does not
        # support %f microsecond (but the datetime module does), use a
        # regular expression substitution to replace instances of %f.
        # Note that this can be useful since python's floating-point
        # precision representation for datetime causes precision to be
        # more accurate closer to year 0 (around the year 2000, precision
        # can be at 10s of microseconds).
        fmt = re.sub(r'((^|[^%])(%%)*)%f',
                     r'\g<1>{0:06d}'.format(dt.microsecond), fmt)

        year = dt.year
        # For every non-leap year century, advance by
        # 6 years to get into the 28-year repeat cycle
        delta = 2000 - year
        off = 6 * (delta // 100 + delta // 400)
        year = year + off

        # Move to between the years 1973 and 2000
        year1 = year + ((2000 - year) // 28) * 28
        year2 = year1 + 28
        timetuple = dt.timetuple()
        # Generate timestamp string for year and year+28
        s1 = time.strftime(fmt, (year1,) + timetuple[1:])
        s2 = time.strftime(fmt, (year2,) + timetuple[1:])

        # Replace instances of respective years (both 2-digit and 4-digit)
        # that are located at the same indexes of s1, s2 with dt's year.
        # Note that C++'s strftime implementation does not use padded
        # zeros or padded whitespace for %y or %Y for years before 100, but
        # uses padded zeros for %x. (For example, try the runnable examples
        # with .tm_year in the interval [-1900, -1800] on
        # http://en.cppreference.com/w/c/chrono/strftime.) For ease of
        # implementation, we always use padded zeros for %y, %Y, and %x.
        s1, s2 = self._replace_common_substr(s1, s2,
                                             "{0:04d}".format(year1),
                                             "{0:04d}".format(year2),
                                             "{0:04d}".format(dt.year))
        s1, s2 = self._replace_common_substr(s1, s2,
                                             "{0:02d}".format(year1 % 100),
                                             "{0:02d}".format(year2 % 100),
                                             "{0:02d}".format(dt.year % 100))
        return cbook.unicode_safe(s1) 
Example 27
Project: coffeegrindsize   Author: jgagneastro   File: dates.py    License: MIT License 4 votes vote down vote up
def strftime_pre_1900(self, dt, fmt=None):
        """Call time.strftime for years before 1900 by rolling
        forward a multiple of 28 years.

        *fmt* is a :func:`strftime` format string.

        Dalke: I hope I did this math right.  Every 28 years the
        calendar repeats, except through century leap years excepting
        the 400 year leap years.  But only if you're using the Gregorian
        calendar.
        """
        if fmt is None:
            fmt = self.fmt

        # Since python's time module's strftime implementation does not
        # support %f microsecond (but the datetime module does), use a
        # regular expression substitution to replace instances of %f.
        # Note that this can be useful since python's floating-point
        # precision representation for datetime causes precision to be
        # more accurate closer to year 0 (around the year 2000, precision
        # can be at 10s of microseconds).
        fmt = re.sub(r'((^|[^%])(%%)*)%f',
                     r'\g<1>{0:06d}'.format(dt.microsecond), fmt)

        year = dt.year
        # For every non-leap year century, advance by
        # 6 years to get into the 28-year repeat cycle
        delta = 2000 - year
        off = 6 * (delta // 100 + delta // 400)
        year = year + off

        # Move to between the years 1973 and 2000
        year1 = year + ((2000 - year) // 28) * 28
        year2 = year1 + 28
        timetuple = dt.timetuple()
        # Generate timestamp string for year and year+28
        s1 = time.strftime(fmt, (year1,) + timetuple[1:])
        s2 = time.strftime(fmt, (year2,) + timetuple[1:])

        # Replace instances of respective years (both 2-digit and 4-digit)
        # that are located at the same indexes of s1, s2 with dt's year.
        # Note that C++'s strftime implementation does not use padded
        # zeros or padded whitespace for %y or %Y for years before 100, but
        # uses padded zeros for %x. (For example, try the runnable examples
        # with .tm_year in the interval [-1900, -1800] on
        # http://en.cppreference.com/w/c/chrono/strftime.) For ease of
        # implementation, we always use padded zeros for %y, %Y, and %x.
        s1, s2 = self._replace_common_substr(s1, s2,
                                             "{0:04d}".format(year1),
                                             "{0:04d}".format(year2),
                                             "{0:04d}".format(dt.year))
        s1, s2 = self._replace_common_substr(s1, s2,
                                             "{0:02d}".format(year1 % 100),
                                             "{0:02d}".format(year2 % 100),
                                             "{0:02d}".format(dt.year % 100))
        return cbook.unicode_safe(s1) 
Example 28
Project: CogAlg   Author: boris-kz   File: dates.py    License: MIT License 4 votes vote down vote up
def strftime_pre_1900(self, dt, fmt=None):
        """Call time.strftime for years before 1900 by rolling
        forward a multiple of 28 years.

        *fmt* is a :func:`strftime` format string.

        Dalke: I hope I did this math right.  Every 28 years the
        calendar repeats, except through century leap years excepting
        the 400 year leap years.  But only if you're using the Gregorian
        calendar.
        """
        if fmt is None:
            fmt = self.fmt

        # Since python's time module's strftime implementation does not
        # support %f microsecond (but the datetime module does), use a
        # regular expression substitution to replace instances of %f.
        # Note that this can be useful since python's floating-point
        # precision representation for datetime causes precision to be
        # more accurate closer to year 0 (around the year 2000, precision
        # can be at 10s of microseconds).
        fmt = re.sub(r'((^|[^%])(%%)*)%f',
                     r'\g<1>{0:06d}'.format(dt.microsecond), fmt)

        year = dt.year
        # For every non-leap year century, advance by
        # 6 years to get into the 28-year repeat cycle
        delta = 2000 - year
        off = 6 * (delta // 100 + delta // 400)
        year = year + off

        # Move to between the years 1973 and 2000
        year1 = year + ((2000 - year) // 28) * 28
        year2 = year1 + 28
        timetuple = dt.timetuple()
        # Generate timestamp string for year and year+28
        s1 = time.strftime(fmt, (year1,) + timetuple[1:])
        s2 = time.strftime(fmt, (year2,) + timetuple[1:])

        # Replace instances of respective years (both 2-digit and 4-digit)
        # that are located at the same indexes of s1, s2 with dt's year.
        # Note that C++'s strftime implementation does not use padded
        # zeros or padded whitespace for %y or %Y for years before 100, but
        # uses padded zeros for %x. (For example, try the runnable examples
        # with .tm_year in the interval [-1900, -1800] on
        # http://en.cppreference.com/w/c/chrono/strftime.) For ease of
        # implementation, we always use padded zeros for %y, %Y, and %x.
        s1, s2 = self._replace_common_substr(s1, s2,
                                             "{0:04d}".format(year1),
                                             "{0:04d}".format(year2),
                                             "{0:04d}".format(dt.year))
        s1, s2 = self._replace_common_substr(s1, s2,
                                             "{0:02d}".format(year1 % 100),
                                             "{0:02d}".format(year2 % 100),
                                             "{0:02d}".format(dt.year % 100))
        return cbook.unicode_safe(s1)