#!/usr/bin/env python
# normalDate.py - version 1.0 - 20000717
_bigBangScalar = -4345732 # based on (-9999, 1, 1) BC/BCE minimum
_bigCrunchScalar = 2958463 # based on (9999,12,31) AD/CE maximum
_daysInMonthNormal = [31,28,31,30,31,30,31,31,30,31,30,31]
_daysInMonthLeapYear = [31,29,31,30,31,30,31,31,30,31,30,31]
_dayOfWeekName = ['Monday', 'Tuesday', 'Wednesday', 'Thursday',
'Friday', 'Saturday', 'Sunday']
_monthName = ['January', 'February', 'March', 'April', 'May', 'June',
'July','August','September','October','November','December']
class NormalDateException(Exception):
"""Exception class for NormalDate"""
pass
class NormalDate:
"""
NormalDate is a specialized class to handle dates without
all the excess baggage (time zones, daylight savings, leap
seconds, etc.) of other date structures. The minimalist
strategy greatly simplifies its implementation and use.
Internally, NormalDate is stored as an integer with values
in a discontinuous range of -99990101 to 99991231. The
integer value is used principally for storage and to simplify
the user interface. Internal calculations are performed by
a scalar based on Jan 1, 1900.
Valid NormalDate ranges include (-9999,1,1) B.C.E. through
(9999,12,31) C.E./A.D.
1.0 - No changes, except the version number. After 3 years of use
by various parties I think we can consider it stable.
0.8 - added Prof. Stephen Walton's suggestion for a range method
- module author resisted the temptation to use lambda <0.5 wink>
0.7 - added Dan Winkler's suggestions for __add__, __sub__ methods
0.6 - modifications suggested by Kevin Digweed to fix:
- dayOfWeek, dayOfWeekAbbrev, clone methods
- permit NormalDate to be a better behaved superclass
0.5 - minor tweaking
0.4 - added methods __cmp__, __hash__
- added Epoch variable, scoped to the module
- added setDay, setMonth, setYear methods
0.3 - minor touch-ups
0.2 - fixed bug for certain B.C.E leap years
- added Jim Fulton's suggestions for short alias class name =ND
and __getstate__, __setstate__ methods
Special thanks: Roedy Green
"""
def __init__(self, normalDate=None):
"""
Accept 1 of 4 values to initialize a NormalDate:
1. None - creates a NormalDate for the current day
2. integer in yyyymmdd format
3. string in yyyymmdd format
4. tuple in (yyyy, mm, dd) - localtime/gmtime can also be used
"""
if normalDate is None:
import time
self.setNormalDate(time.localtime(time.time()))
else:
self.setNormalDate(normalDate)
def add(self, days):
"""add days to date; use negative integers to subtract"""
if not type(days) is type(0):
raise NormalDateException( \
'add method parameter must be integer type')
self.normalize(self.scalar() + days)
def __add__(self, days):
"""add integer to normalDate and return a new, calculated value"""
if not type(days) is type(0):
raise NormalDateException( \
'__add__ parameter must be integer type')
cloned = self.clone()
cloned.add(days)
return cloned
def clone(self):
"""return a cloned instance of this normalDate"""
return self.__class__(self.normalDate)
def __cmp__(self, target):
if target is None:
return 1
elif not hasattr(target, 'normalDate'):
return 1
else:
return cmp(self.normalDate, target.normalDate)
def day(self):
"""return the day as integer 1-31"""
return int(repr(self.normalDate)[-2:])
def dayOfWeek(self):
"""return integer representing day of week, Mon=0, Tue=1, etc."""
return apply(dayOfWeek, self.toTuple())
def dayOfWeekAbbrev(self):
"""return day of week abbreviation for current date: Mon, Tue, etc."""
return _dayOfWeekName[self.dayOfWeek()][:3]
def dayOfWeekName(self):
"""return day of week name for current date: Monday, Tuesday, etc."""
return _dayOfWeekName[self.dayOfWeek()]
def dayOfYear(self):
"""day of year"""
if self.isLeapYear():
daysByMonth = _daysInMonthLeapYear
else:
daysByMonth = _daysInMonthNormal
priorMonthDays = 0
for m in xrange(self.month() - 1):
priorMonthDays = priorMonthDays + daysByMonth[m]
return self.day() + priorMonthDays
def daysBetweenDates(self, normalDate):
"""
return value may be negative, since calculation is
self.scalar() - arg
"""
if type(normalDate) is type(self):
return self.scalar() - normalDate.scalar()
else:
return self.scalar() - NormalDate(normalDate).scalar()
def equals(self, target):
if type(target) is type(self):
if target is None:
return self.normalDate is None
else:
return self.normalDate == target.normalDate
else:
return 0
def endOfMonth(self):
"""returns (cloned) last day of month"""
return NormalDate(self.__repr__()[-8:-2]+str(self.lastDayOfMonth()))
def firstDayOfMonth(self):
"""returns (cloned) first day of month"""
return NormalDate(self.__repr__()[-8:-2]+"01")
def formatUS(self):
"""return date as string in common US format: MM/DD/YY"""
d = self.__repr__()
return "%s/%s/%s" % (d[-4:-2], d[-2:], d[-6:-4])
def formatUSCentury(self):
"""return date as string in 4-digit year US format: MM/DD/YYYY"""
d = self.__repr__()
return "%s/%s/%s" % (d[-4:-2], d[-2:], d[-8:-4])
def __getstate__(self):
"""minimize persistent storage requirements"""
return self.normalDate
def __hash__(self):
return hash(self.normalDate)
def __int__(self):
return self.normalDate
def isLeapYear(self):
"""
determine if specified year is leap year, returning true (1) or
false (0)
"""
return isLeapYear(self.year())
def _isValidNormalDate(self, normalDate):
"""checks for date validity in [-]yyyymmdd format"""
if type(normalDate) is not type(0):
return 0
if len(repr(normalDate)) > 9:
return 0
if normalDate < 0:
dateStr = "%09d" % normalDate
else:
dateStr = "%08d" % normalDate
if len(dateStr) < 8:
return 0
elif len(dateStr) == 9:
if (dateStr[0] != '-' and dateStr[0] != '+'):
return 0
year = int(dateStr[:-4])
if year < -9999 or year > 9999 or year == 0:
return 0 # note: zero (0) is not a valid year
month = int(dateStr[-4:-2])
if month < 1 or month > 12:
return 0
if isLeapYear(year):
maxDay = _daysInMonthLeapYear[month - 1]
else:
maxDay = _daysInMonthNormal[month - 1]
day = int(dateStr[-2:])
if day < 1 or day > maxDay:
return 0
if year == 1582 and month == 10 and day > 4 and day < 15:
return 0 # special case of 10 days dropped: Oct 5-14, 1582
return 1
def lastDayOfMonth(self):
"""returns last day of the month as integer 28-31"""
if self.isLeapYear():
return _daysInMonthLeapYear[self.month() - 1]
else:
return _daysInMonthNormal[self.month() - 1]
def localeFormat(self):
"""override this method to use your preferred locale format"""
return self.formatUS()
def month(self):
"""returns month as integer 1-12"""
return int(repr(self.normalDate)[-4:-2])
def monthAbbrev(self):
"""returns month as a 3-character abbreviation, i.e. Jan, Feb, etc."""
return _monthName[self.month() - 1][:3]
def monthName(self):
"""returns month name, i.e. January, February, etc."""
return _monthName[self.month() - 1]
def normalize(self, scalar):
"""convert scalar to normalDate"""
if scalar < _bigBangScalar:
msg = "normalize(%d): scalar below minimum" % \
_bigBangScalar
raise NormalDateException(msg)
if scalar > _bigCrunchScalar:
msg = "normalize(%d): scalar exceeds maximum" % \
_bigCrunchScalar
raise NormalDateException(msg)
from math import floor
if scalar >= -115860:
year = 1600 + int(floor((scalar + 109573) / 365.2425))
elif scalar >= -693597:
year = 4 + int(floor((scalar + 692502) / 365.2425))
else:
year = -4 + int(floor((scalar + 695058) / 365.2425))
days = scalar - firstDayOfYear(year) + 1
if days <= 0:
year = year - 1
days = scalar - firstDayOfYear(year) + 1
daysInYear = 365
if isLeapYear(year):
daysInYear = daysInYear + 1
if days > daysInYear:
year = year + 1
days = scalar - firstDayOfYear(year) + 1
# add 10 days if between Oct 15, 1582 and Dec 31, 1582
if (scalar >= -115860 and scalar <= -115783):
days = days + 10
if isLeapYear(year):
daysByMonth = _daysInMonthLeapYear
else:
daysByMonth = _daysInMonthNormal
dc = 0; month = 12
for m in xrange(len(daysByMonth)):
dc = dc + daysByMonth[m]
if dc >= days:
month = m + 1
break
# add up the days in prior months
priorMonthDays = 0
for m in xrange(month - 1):
priorMonthDays = priorMonthDays + daysByMonth[m]
day = days - priorMonthDays
self.setNormalDate((year, month, day))
def range(self, days):
"""Return a range of normalDates as a list. Parameter
may be an int or normalDate."""
if type(days) is not type(0):
days = days - self # if not int, assume arg is normalDate type
r = []
for i in range(days):
r.append(self + i)
return r
def __repr__(self):
"""print format: [-]yyyymmdd"""
# Note: When disassembling a NormalDate string, be sure to
# count from the right, i.e. epochMonth = int(`Epoch`[-4:-2]),
# or the slice won't work for dates B.C.
if self.normalDate < 0:
return "%09d" % self.normalDate
else:
return "%08d" % self.normalDate
def scalar(self):
"""days since baseline date: Jan 1, 1900"""
(year, month, day) = self.toTuple()
days = firstDayOfYear(year) + day - 1
if self.isLeapYear():
for m in xrange(month - 1):
days = days + _daysInMonthLeapYear[m]
else:
for m in xrange(month - 1):
days = days + _daysInMonthNormal[m]
if year == 1582:
if month > 10 or (month == 10 and day > 4):
days = days - 10
return days
def setDay(self, day):
"""set the day of the month"""
maxDay = self.lastDayOfMonth()
if day < 1 or day > maxDay:
msg = "day is outside of range 1 to %d" % maxDay
raise NormalDateException(msg)
(y, m, d) = self.toTuple()
self.setNormalDate((y, m, day))
def setMonth(self, month):
"""set the month [1-12]"""
if month < 1 or month > 12:
raise NormalDateException('month is outside range 1 to 12')
(y, m, d) = self.toTuple()
self.setNormalDate((y, month, d))
def setNormalDate(self, normalDate):
"""
accepts date as scalar string/integer (yyyymmdd) or tuple
(year, month, day, ...)"""
import time
import sys
if type(normalDate) is type(0):
self.normalDate = normalDate
elif type(normalDate) is type(''):
self.normalDate = int(normalDate)
elif type(normalDate) is type(()):
self.normalDate = int("%04d%02d%02d" % normalDate[:3])
elif type(normalDate) is type(self):
self.normalDate = normalDate.normalDate
elif(sys.version_info[0] == 2 and sys.version_info[1] > 1):
# In Python 2.2 and later, the time tuple isn't a tuple,
# its of type 'time.struct_time'. Make sure we test this
# or this doesn't work.
if type(normalDate) is time.struct_time:
self.normalDate = int("%04d%02d%02d" % normalDate[:3])
if not self._isValidNormalDate(self.normalDate):
msg = "unable to setNormalDate(%s)" % `normalDate`
raise NormalDateException(msg)
def setYear(self, year):
if year == 0:
raise NormalDateException('cannot set year to zero')
elif year < -9999:
raise NormalDateException('year cannot be less than -9999')
elif year > 9999:
raise NormalDateException('year cannot be greater than 9999')
(y, m, d) = self.toTuple()
self.setNormalDate((year, m, d))
__setstate__ = setNormalDate
def __sub__(self, v):
if type(v) is type(0):
return self.__add__(-v)
return self.scalar() - v.scalar()
def toTuple(self):
"""return date as (year, month, day) tuple"""
return (self.year(), self.month(), self.day())
def year(self):
"""return year in yyyy format, negative values indicate B.C."""
return int(repr(self.normalDate)[:-4])
ND=NormalDate
################# Utility functions #################
def bigBang():
"""return lower boundary as a NormalDate"""
return NormalDate((-9999, 1, 1))
def bigCrunch():
"""return upper boundary as a NormalDate"""
return NormalDate((9999, 12, 31))
def dayOfWeek(y, m, d):
"""return integer representing day of week, Mon=0, Tue=1, etc."""
if m == 1 or m == 2:
m = m + 12
y = y - 1
return (d + 2*m + 3*(m+1)/5 + y + y/4 - y/100 + y/400) % 7
def firstDayOfYear(year):
"""number of days to the first of the year, relative to Jan 1, 1900"""
if type(year) is not type(0):
msg = "firstDayOfYear() expected integer, got %s" % type(year)
raise NormalDateException(msg)
if year == 0:
raise NormalDateException('first day of year cannot be zero (0)')
elif year < 0: # BCE calculation
firstDay = (year * 365) + int((year - 1) / 4) - 693596
else: # CE calculation
leapAdjust = int((year + 3) / 4)
if year > 1600:
leapAdjust = leapAdjust - int((year + 99 - 1600) / 100) + \
int((year + 399 - 1600) / 400)
firstDay = year * 365 + leapAdjust - 693963
if year > 1582:
firstDay = firstDay - 10
return firstDay
def isLeapYear(year):
"""determine if specified year is leap year, returns Python boolean"""
if year < 1600:
if year % 4:
return 0
else:
return 1
elif year % 4 != 0:
return 0
elif year % 100 != 0:
return 1
elif year % 400 != 0:
return 0
else:
return 1
Epoch=bigBang()
if __name__ == '__main__':
today = NormalDate()
print "NormalDate test:"
print " Today (%s) is: %s %s" % \
(today, today.dayOfWeekAbbrev(), today.localeFormat())
yesterday = today - 1
print " Yesterday was: %s %s" % \
(yesterday.dayOfWeekAbbrev(), yesterday.localeFormat())
tomorrow = today + 1
print " Tomorrow will be: %s %s" % \
(tomorrow.dayOfWeekAbbrev(), tomorrow.localeFormat())
print " Days between tomorrow and yesterday: %d" % \
(tomorrow - yesterday)