diff options
Diffstat (limited to 'Assignment 3/packages/xlrd/xldate.py')
| -rw-r--r-- | Assignment 3/packages/xlrd/xldate.py | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/Assignment 3/packages/xlrd/xldate.py b/Assignment 3/packages/xlrd/xldate.py new file mode 100644 index 0000000..dc7b9c8 --- /dev/null +++ b/Assignment 3/packages/xlrd/xldate.py @@ -0,0 +1,213 @@ +# -*- coding: cp1252 -*- + +# No part of the content of this file was derived from the works of David Giffin. + +## +# <p>Copyright © 2005-2008 Stephen John Machin, Lingfo Pty Ltd</p> +# <p>This module is part of the xlrd package, which is released under a BSD-style licence.</p> +# +# <p>Provides function(s) for dealing with Microsoft Excel ™ dates.</p> +## + +# 2008-10-18 SJM Fix bug in xldate_from_date_tuple (affected some years after 2099) + +# 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) + +class XLDateError(ValueError): pass + +class XLDateNegative(XLDateError): pass +class XLDateAmbiguous(XLDateError): pass +class XLDateTooLarge(XLDateError): pass +class XLDateBadDatemode(XLDateError): pass +class XLDateBadTuple(XLDateError): pass + +_XLDAYS_TOO_LARGE = (2958466, 2958466 - 1462) # This is equivalent to 10000-01-01 + +## +# 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. +# <br>WARNING: when using this function to +# interpret the contents of a workbook, you should pass in the Book.datemode +# attribute of that workbook. Whether +# the workbook has ever been anywhere near a Macintosh is irrelevant. +# @return Gregorian (year, month, day, hour, minute, nearest_second). +# <br>Special case: if 0.0 <= xldate < 1.0, it is assumed to represent a time; +# (0, 0, 0, hour, minute, second) will be returned. +# <br>Note: 1904-01-01 is not regarded as a valid date in the datemode 1 system; its "serial number" +# is zero. +# @throws XLDateNegative xldate < 0.00 +# @throws XLDateAmbiguous The 1900 leap-year problem (datemode == 0 and 1.0 <= xldate < 61.0) +# @throws XLDateTooLarge Gregorian year 10000 or later +# @throws XLDateBadDatemode datemode arg is neither 0 nor 1 +# @throws XLDateError Covers the 4 specific errors + +def xldate_as_tuple(xldate, datemode): + 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) + + +## +# Convert an Excel date/time number into a datetime.datetime object. +# +# @param xldate The Excel number +# @param datemode 0: 1900-based, 1: 1904-based. +# +# @return a datetime.datetime() object. +# +def xldate_as_datetime(xldate, datemode): + """Convert an Excel date/time number into a 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) + +## +# 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. +# @throws XLDateAmbiguous The 1900 leap-year problem (datemode == 0 and 1.0 <= xldate < 61.0) +# @throws XLDateBadDatemode datemode arg is neither 0 nor 1 +# @throws XLDateBadTuple (year, month, day) is too early/late or has invalid component(s) +# @throws XLDateError Covers the specific errors + +def xldate_from_date_tuple(date_tuple, datemode): + """Create an excel date from a tuple of (year, month, day)""" + 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) + +## +# 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 +# @throws XLDateBadTuple Out-of-range hour, minute, or second + +def xldate_from_time_tuple(time_tuple): + """Create an excel date from a tuple of (hour, minute, 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),)) + +## +# 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. + +def xldate_from_datetime_tuple(datetime_tuple, datemode): + return ( + xldate_from_date_tuple(datetime_tuple[:3], datemode) + + + xldate_from_time_tuple(datetime_tuple[3:]) + ) |