# -*- coding: utf-8 -*-
# Copyright (c) 2005-2008 Stephen John Machin, Lingfo Pty Ltd
# This module is part of the xlrd package, which is released under a
# BSD-style licence.
# No part of the content of this file was derived from the works of David Giffin.
"""
Tools for working with dates and times in Excel files.
The conversion from ``days`` to ``(year, month, day)`` starts with
an integral "julian day number" aka JDN.
FWIW:
- JDN 0 corresponds to noon on Monday November 24 in Gregorian year -4713.
More importantly:
- Noon on Gregorian 1900-03-01 (day 61 in the 1900-based system) is JDN 2415080.0
- Noon on Gregorian 1904-01-02 (day 1 in the 1904-based system) is JDN 2416482.0
"""
import datetime
_JDN_delta = (2415080 - 61, 2416482 - 1)
assert _JDN_delta[1] - _JDN_delta[0] == 1462
# Pre-calculate the datetime epochs for efficiency.
epoch_1904 = datetime.datetime(1904, 1, 1)
epoch_1900 = datetime.datetime(1899, 12, 31)
epoch_1900_minus_1 = datetime.datetime(1899, 12, 30)
# This is equivalent to 10000-01-01:
_XLDAYS_TOO_LARGE = (2958466, 2958466 - 1462)
class XLDateError(ValueError):
"A base class for all datetime-related errors."
class XLDateNegative(XLDateError):
"``xldate < 0.00``"
class XLDateAmbiguous(XLDateError):
"The 1900 leap-year problem ``(datemode == 0 and 1.0 <= xldate < 61.0)``"
class XLDateTooLarge(XLDateError):
"Gregorian year 10000 or later"
class XLDateBadDatemode(XLDateError):
"``datemode`` arg is neither 0 nor 1"
class XLDateBadTuple(XLDateError):
pass
def xldate_as_tuple(xldate, datemode):
"""
Convert an Excel number (presumed to represent a date, a datetime or a time) into
a tuple suitable for feeding to datetime or mx.DateTime constructors.
:param xldate: The Excel number
:param datemode: 0: 1900-based, 1: 1904-based.
:raises xlrd.xldate.XLDateNegative:
:raises xlrd.xldate.XLDateAmbiguous:
:raises xlrd.xldate.XLDateTooLarge:
:raises xlrd.xldate.XLDateBadDatemode:
:raises xlrd.xldate.XLDateError:
:returns: Gregorian ``(year, month, day, hour, minute, nearest_second)``.
.. warning::
When using this function to interpret the contents of a workbook, you
should pass in the :attr:`~xlrd.book.Book.datemode`
attribute of that workbook. Whether the workbook has ever been anywhere
near a Macintosh is irrelevant.
.. admonition:: Special case
If ``0.0 <= xldate < 1.0``, it is assumed to represent a time;
``(0, 0, 0, hour, minute, second)`` will be returned.
.. note::
``1904-01-01`` is not regarded as a valid date in the ``datemode==1``
system; its "serial number" is zero.
"""
if datemode not in (0, 1):
raise XLDateBadDatemode(datemode)
if xldate == 0.00:
return (0, 0, 0, 0, 0, 0)
if xldate < 0.00:
raise XLDateNegative(xldate)
xldays = int(xldate)
frac = xldate - xldays
seconds = int(round(frac * 86400.0))
assert 0 <= seconds <= 86400
if seconds == 86400:
hour = minute = second = 0
xldays += 1
else:
# second = seconds % 60; minutes = seconds // 60
minutes, second = divmod(seconds, 60)
# minute = minutes % 60; hour = minutes // 60
hour, minute = divmod(minutes, 60)
if xldays >= _XLDAYS_TOO_LARGE[datemode]:
raise XLDateTooLarge(xldate)
if xldays == 0:
return (0, 0, 0, hour, minute, second)
if xldays < 61 and datemode == 0:
raise XLDateAmbiguous(xldate)
jdn = xldays + _JDN_delta[datemode]
yreg = ((((jdn * 4 + 274277) // 146097) * 3 // 4) + jdn + 1363) * 4 + 3
mp = ((yreg % 1461) // 4) * 535 + 333
d = ((mp % 16384) // 535) + 1
# mp /= 16384
mp >>= 14
if mp >= 10:
return ((yreg // 1461) - 4715, mp - 9, d, hour, minute, second)
else:
return ((yreg // 1461) - 4716, mp + 3, d, hour, minute, second)
def xldate_as_datetime(xldate, datemode):
"""
Convert an Excel date/time number into a :class:`datetime.datetime` object.
:param xldate: The Excel number
:param datemode: 0: 1900-based, 1: 1904-based.
:returns: A :class:`datetime.datetime` object.
"""
# Set the epoch based on the 1900/1904 datemode.
if datemode:
epoch = epoch_1904
else:
if xldate < 60:
epoch = epoch_1900
else:
# Workaround Excel 1900 leap year bug by adjusting the epoch.
epoch = epoch_1900_minus_1
# The integer part of the Excel date stores the number of days since
# the epoch and the fractional part stores the percentage of the day.
days = int(xldate)
fraction = xldate - days
# Get the the integer and decimal seconds in Excel's millisecond resolution.
seconds = int(round(fraction * 86400000.0))
seconds, milliseconds = divmod(seconds, 1000)
return epoch + datetime.timedelta(days, seconds, 0, milliseconds)
# === conversions from date/time to xl numbers
def _leap(y):
if y % 4: return 0
if y % 100: return 1
if y % 400: return 0
return 1
_days_in_month = (None, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
def xldate_from_date_tuple(date_tuple, datemode):
"""
Convert a date tuple (year, month, day) to an Excel date.
:param year: Gregorian year.
:param month: ``1 <= month <= 12``
:param day: ``1 <= day <= last day of that (year, month)``
:param datemode: 0: 1900-based, 1: 1904-based.
:raises xlrd.xldate.XLDateAmbiguous:
:raises xlrd.xldate.XLDateBadDatemode:
:raises xlrd.xldate.XLDateBadTuple:
``(year, month, day)`` is too early/late or has invalid component(s)
:raises xlrd.xldate.XLDateError:
"""
year, month, day = date_tuple
if datemode not in (0, 1):
raise XLDateBadDatemode(datemode)
if year == 0 and month == 0 and day == 0:
return 0.00
if not (1900 <= year <= 9999):
raise XLDateBadTuple("Invalid year: %r" % ((year, month, day),))
if not (1 <= month <= 12):
raise XLDateBadTuple("Invalid month: %r" % ((year, month, day),))
if (day < 1 or
(day > _days_in_month[month] and not(day == 29 and month == 2 and _leap(year)))):
raise XLDateBadTuple("Invalid day: %r" % ((year, month, day),))
Yp = year + 4716
M = month
if M <= 2:
Yp = Yp - 1
Mp = M + 9
else:
Mp = M - 3
jdn = (1461 * Yp // 4) + ((979 * Mp + 16) // 32) + \
day - 1364 - (((Yp + 184) // 100) * 3 // 4)
xldays = jdn - _JDN_delta[datemode]
if xldays <= 0:
raise XLDateBadTuple("Invalid (year, month, day): %r" % ((year, month, day),))
if xldays < 61 and datemode == 0:
raise XLDateAmbiguous("Before 1900-03-01: %r" % ((year, month, day),))
return float(xldays)
def xldate_from_time_tuple(time_tuple):
"""
Convert a time tuple ``(hour, minute, second)`` to an Excel "date" value
(fraction of a day).
:param hour: ``0 <= hour < 24``
:param minute: ``0 <= minute < 60``
:param second: ``0 <= second < 60``
:raises xlrd.xldate.XLDateBadTuple: Out-of-range hour, minute, or second
"""
hour, minute, second = time_tuple
if 0 <= hour < 24 and 0 <= minute < 60 and 0 <= second < 60:
return ((second / 60.0 + minute) / 60.0 + hour) / 24.0
raise XLDateBadTuple("Invalid (hour, minute, second): %r" % ((hour, minute, second),))
def xldate_from_datetime_tuple(datetime_tuple, datemode):
"""
Convert a datetime tuple ``(year, month, day, hour, minute, second)`` to an
Excel date value.
For more details, refer to other xldate_from_*_tuple functions.
:param datetime_tuple: ``(year, month, day, hour, minute, second)``
:param datemode: 0: 1900-based, 1: 1904-based.
"""
return (
xldate_from_date_tuple(datetime_tuple[:3], datemode) +
xldate_from_time_tuple(datetime_tuple[3:])
)