pax_global_header00006660000000000000000000000064116437723770014533gustar00rootroot0000000000000052 comment=81298bc9c10c4a39823a5585b9c90e229e1f657b jdcal-1.0/000077500000000000000000000000001164377237700124505ustar00rootroot00000000000000jdcal-1.0/.gitignore000066400000000000000000000000041164377237700144320ustar00rootroot00000000000000.pycjdcal-1.0/MANIFEST000066400000000000000000000000351164377237700135770ustar00rootroot00000000000000jdcal.py setup.py README.rst jdcal-1.0/README.rst000066400000000000000000000071531164377237700141450ustar00rootroot00000000000000jdcal ===== .. _TPM: http://www.sal.wisc.edu/~jwp/astro/tpm/tpm.html .. _Jeffrey W. Percival: http://www.sal.wisc.edu/~jwp/ .. _IAU SOFA: http://www.iausofa.org/ .. _pip: http://pypi.python.org/pypi/pip .. _easy_install: packages.python.org/distribute/easy_install.html This module contains functions for converting between Julian dates and calendar dates. A function for converting Gregorian calendar dates to Julian dates, and another function for converting Julian calendar dates to Julian dates are defined. Two functions for the reverse calculations are also defined. Different regions of the world switched to Gregorian calendar from Julian calendar on different dates. Having separate functions for Julian and Gregorian calendars allow maximum flexibility in choosing the relevant calendar. Julian dates are stored in two floating point numbers (double). Julian dates, and Modified Julian dates, are large numbers. If only one number is used, then the precision of the time stored is limited. Using two numbers, time can be split in a manner that will allow maximum precision. For example, the first number could be the Julian date for the beginning of a day and the second number could be the fractional day. Calculations that need the latter part can now work with maximum precision. All the above functions are "proleptic". This means that they work for dates on which the concerned calendar is not valid. For example, Gregorian calendar was not used prior to around October 1582. A function to test if a given Gregorian calendar year is a leap year is also defined. Zero point of Modified Julian Date (MJD) and the MJD of 2000/1/1 12:00:00 are also given as module level constants. Examples -------- Some examples are given below. For more information see http://oneau.wordpress.com/jdcal/. Gregorian calendar:: >>> gcal2jd(2000,1,1) (2400000.5, 51544.0) >>> 2400000.5 + 51544.0 + 0.5 2451545.0 >>> gcal2jd(2000,2,30) (2400000.5, 51604.0) >>> gcal2jd(2000,3,1) (2400000.5, 51604.0) >>> gcal2jd(2001,2,30) (2400000.5, 51970.0) >>> gcal2jd(2001,3,2) (2400000.5, 51970.0) >>> jd2gcal(*gcal2jd(2000,1,1)) (2000, 1, 1, 0.0) >>> jd2gcal(*gcal2jd(1950,1,1)) (1950, 1, 1, 0.0) >>> gcal2jd(2000,1,1) (2400000.5, 51544.0) >>> jd2gcal(2400000.5, 51544.0) (2000, 1, 1, 0.0) >>> jd2gcal(2400000.5, 51544.5) (2000, 1, 1, 0.5) >>> jd2gcal(2400000.5, 51544.245) (2000, 1, 1, 0.24500000000261934) >>> jd2gcal(2400000.5, 51544.1) (2000, 1, 1, 0.099999999998544808) >>> jd2gcal(2400000.5, 51544.75) (2000, 1, 1, 0.75) Julian calendar:: >>> jd2jcal(*jcal2jd(2000, 1, 1)) (2000, 1, 1, 0.0) >>> jd2jcal(*jcal2jd(-4000, 10, 11)) (-4000, 10, 11, 0.0) Gregorian leap year:: >>> is_leap(2000) True >>> is_leap(2100) False JD for zero point of MJD, and MJD for JD2000.0:: >>> print MJD_0 2400000.5 >>> print MJD_JD2000 51544.5 Installation ------------ The module can be installed using `pip`_ or `easy_install`_:: $ pip install jdcal or, :: $ easy_install jdcal Credits -------- 1. A good amount of the code is based on the excellent `TPM`_ C library by `Jeffrey W. Percival`_. A Python interface to this C library is available at http://github.com/phn/pytpm. 2. The inspiration to split Julian dates into two numbers came from the `IAU SOFA`_ C library. No code or algorithm from the SOFA library is used in `jdcal`. License ------- Released under BSD; see http://www.opensource.org/licenses/bsd-license.php. For comments and suggestions, email to user `prasanthhn` in the `gmail.com` domain. jdcal-1.0/jdcal.py000066400000000000000000000350671164377237700141120ustar00rootroot00000000000000# -*- coding:utf-8 -*- """Functions for converting between Julian dates and calendar dates. A function for converting Gregorian calendar dates to Julian dates, and another function for converting Julian calendar dates to Julian dates are defined. Two functions for the reverse calculations are also defined. Different regions of the world switched to Gregorian calendar from Julian calendar on different dates. Having separate functions for Julian and Gregorian calendars allow maximum flexibility in choosing the relevant calendar. All the above functions are "proleptic". This means that they work for dates on which the concerned calendar is not valid. For example, Gregorian calendar was not used prior to around October 1582. Julian dates are stored in two floating point numbers (double). Julian dates, and Modified Julian dates, are large numbers. If only one number is used, then the precision of the time stored is limited. Using two numbers, time can be split in a manner that will allow maximum precision. For example, the first number could be the Julian date for the beginning of a day and the second number could be the fractional day. Calculations that need the latter part can now work with maximum precision. A function to test if a given Gregorian calendar year is a leap year is defined. Zero point of Modified Julian Date (MJD) and the MJD of 2000/1/1 12:00:00 are also given. This module is based on the TPM C library, by Jeffery W. Percival. The idea for splitting Julian date into two floating point numbers was inspired by the IAU SOFA C library. :author: Prasanth Nair :contact: prasanthhn@gmail.com :license: BSD (http://www.opensource.org/licenses/bsd-license.php) """ from __future__ import division from __future__ import print_function import math __version__ = "1.0" MJD_0 = 2400000.5 MJD_JD2000 = 51544.5 def fpart(x): """Return fractional part of given number.""" return math.modf(x)[0] def ipart(x): """Return integer part of given number.""" return math.modf(x)[1] def is_leap(year): """Leap year or not in the Gregorian calendar.""" x = math.fmod(year, 4) y = math.fmod(year, 100) z = math.fmod(year, 400) # Divisible by 4 and, # either not divisible by 100 or divisible by 400. return not x and (y or not z) def gcal2jd(year, month, day): """Gregorian calendar date to Julian date. The input and output are for the proleptic Gregorian calendar, i.e., no consideration of historical usage of the calendar is made. Parameters ---------- year : int Year as an integer. month : int Month as an integer. day : int Day as an integer. Returns ------- jd1, jd2: 2-element tuple of floats When added together, the numbers give the Julian date for the given Gregorian calendar date. The first number is always MJD_0 i.e., 2451545.5. So the second is the MJD. Examples -------- >>> gcal2jd(2000,1,1) (2400000.5, 51544.0) >>> 2400000.5 + 51544.0 + 0.5 2451545.0 >>> year = [-4699, -2114, -1050, -123, -1, 0, 1, 123, 1678.0, 2000, ....: 2012, 2245] >>> month = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] >>> day = [1, 12, 23, 14, 25, 16, 27, 8, 9, 10, 11, 31] >>> x = [gcal2jd(y, m, d) for y, m, d in zip(year, month, day)] >>> for i in x: print i (2400000.5, -2395215.0) (2400000.5, -1451021.0) (2400000.5, -1062364.0) (2400000.5, -723762.0) (2400000.5, -679162.0) (2400000.5, -678774.0) (2400000.5, -678368.0) (2400000.5, -633797.0) (2400000.5, -65812.0) (2400000.5, 51827.0) (2400000.5, 56242.0) (2400000.5, 141393.0) Negative months and days are valid. For example, 2000/-2/-4 => 1999/+12-2/-4 => 1999/10/-4 => 1999/9/30-4 => 1999/9/26. >>> gcal2jd(2000, -2, -4) (2400000.5, 51447.0) >>> gcal2jd(1999, 9, 26) (2400000.5, 51447.0) >>> gcal2jd(2000, 2, -1) (2400000.5, 51573.0) >>> gcal2jd(2000, 1, 30) (2400000.5, 51573.0) >>> gcal2jd(2000, 3, -1) (2400000.5, 51602.0) >>> gcal2jd(2000, 2, 28) (2400000.5, 51602.0) Month 0 becomes previous month. >>> gcal2jd(2000, 0, 1) (2400000.5, 51513.0) >>> gcal2jd(1999, 12, 1) (2400000.5, 51513.0) Day number 0 becomes last day of previous month. >>> gcal2jd(2000, 3, 0) (2400000.5, 51603.0) >>> gcal2jd(2000, 2, 29) (2400000.5, 51603.0) If `day` is greater than the number of days in `month`, then it gets carried over to the next month. >>> gcal2jd(2000,2,30) (2400000.5, 51604.0) >>> gcal2jd(2000,3,1) (2400000.5, 51604.0) >>> gcal2jd(2001,2,30) (2400000.5, 51970.0) >>> gcal2jd(2001,3,2) (2400000.5, 51970.0) Notes ----- The returned Julian date is for mid-night of the given date. To find the Julian date for any time of the day, simply add time as a fraction of a day. For example Julian date for mid-day can be obtained by adding 0.5 to either the first part or the second part. The latter is preferable, since it will give the MJD for the date and time. BC dates should be given as -(BC - 1) where BC is the year. For example 1 BC == 0, 2 BC == -1, and so on. Negative numbers can be used for `month` and `day`. For example 2000, -1, 1 is the same as 1999, 11, 1. The Julian dates are proleptic Julian dates, i.e., values are returned without considering if Gregorian dates are valid for the given date. The input values are truncated to integers. """ year = int(year) month = int(month) day = int(day) a = ipart((month - 14) / 12.0) jd = ipart((1461 * (year + 4800 + a)) / 4.0) jd += ipart((367 * (month - 2 - 12 * a)) / 12.0) x = ipart((year + 4900 + a) / 100.0) jd -= ipart((3 * x) / 4.0) jd += day - 2432075.5 # was 32075; add 2400000.5 jd -= 0.5 # 0 hours; above JD is for midday, switch to midnight. return MJD_0, jd def jd2gcal(jd1, jd2): """Julian date to Gregorian calendar date and time of day. The input and output are for the proleptic Gregorian calendar, i.e., no consideration of historical usage of the calendar is made. Parameters ---------- jd1, jd2: int Sum of the two numbers is taken as the given Julian date. For example `jd1` can be the zero point of MJD (MJD_0) and `jd2` can be the MJD of the date and time. But any combination will work. Returns ------- y, m, d, f : int, int, int, float Four element tuple containing year, month, day and the fractional part of the day in the Gregorian calendar. The first three are integers, and the last part is a float. Examples -------- >>> jd2gcal(*gcal2jd(2000,1,1)) (2000, 1, 1, 0.0) >>> jd2gcal(*gcal2jd(1950,1,1)) (1950, 1, 1, 0.0) Out of range months and days are carried over to the next/previous year or next/previous month. See gcal2jd for more examples. >>> jd2gcal(*gcal2jd(1999,10,12)) (1999, 10, 12, 0.0) >>> jd2gcal(*gcal2jd(2000,2,30)) (2000, 3, 1, 0.0) >>> jd2gcal(*gcal2jd(-1999,10,12)) (-1999, 10, 12, 0.0) >>> jd2gcal(*gcal2jd(2000, -2, -4)) (1999, 9, 26, 0.0) >>> gcal2jd(2000,1,1) (2400000.5, 51544.0) >>> jd2gcal(2400000.5, 51544.0) (2000, 1, 1, 0.0) >>> jd2gcal(2400000.5, 51544.5) (2000, 1, 1, 0.5) >>> jd2gcal(2400000.5, 51544.245) (2000, 1, 1, 0.24500000000261934) >>> jd2gcal(2400000.5, 51544.1) (2000, 1, 1, 0.099999999998544808) >>> jd2gcal(2400000.5, 51544.75) (2000, 1, 1, 0.75) Notes ----- The last element of the tuple is the same as (hh + mm / 60.0 + ss / 3600.0) / 24.0 where hh, mm, and ss are the hour, minute and second of the day. See Also -------- gcal2jd """ from math import modf jd1_f, jd1_i = modf(jd1) jd2_f, jd2_i = modf(jd2) jd_i = jd1_i + jd2_i f = jd1_f + jd2_f # Set JD to noon of the current date. Fractional part is the # fraction from midnight of the current date. if -0.5 < f < 0.5: f += 0.5 elif f >= 0.5: jd_i += 1 f -= 0.5 elif f <= -0.5: jd_i -= 1 f += 1.5 l = jd_i + 68569 n = ipart((4 * l) / 146097.0) l -= ipart(((146097 * n) + 3) / 4.0) i = ipart((4000 * (l + 1)) / 1461001) l -= ipart((1461 * i) / 4.0) - 31 j = ipart((80 * l) / 2447.0) day = l - ipart((2447 * j) / 80.0) l = ipart(j / 11.0) month = j + 2 - (12 * l) year = 100 * (n - 49) + i + l return int(year), int(month), int(day), f def jcal2jd(year, month, day): """Julian calendar date to Julian date. The input and output are for the proleptic Julian calendar, i.e., no consideration of historical usage of the calendar is made. Parameters ---------- year : int Year as an integer. month : int Month as an integer. day : int Day as an integer. Returns ------- jd1, jd2: 2-element tuple of floats When added together, the numbers give the Julian date for the given Julian calendar date. The first number is always MJD_0 i.e., 2451545.5. So the second is the MJD. Examples -------- >>> jcal2jd(2000, 1, 1) (2400000.5, 51557.0) >>> year = [-4699, -2114, -1050, -123, -1, 0, 1, 123, 1678, 2000, ...: 2012, 2245] >>> month = [1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12] >>> day = [1, 12, 23, 14, 25, 16, 27, 8, 9, 10, 11, 31] >>> x = [jcal2jd(y, m, d) for y, m, d in zip(year, month, day)] >>> for i in x: print i (2400000.5, -2395252.0) (2400000.5, -1451039.0) (2400000.5, -1062374.0) (2400000.5, -723765.0) (2400000.5, -679164.0) (2400000.5, -678776.0) (2400000.5, -678370.0) (2400000.5, -633798.0) (2400000.5, -65772.0) (2400000.5, 51871.0) (2400000.5, 56285.0) Notes ----- Unlike `gcal2jd`, negative months and days can result in incorrect Julian dates. """ year = int(year) month = int(month) day = int(day) jd = 367 * year x = ipart((month - 9) / 7.0) jd -= ipart((7 * (year + 5001 + x)) / 4.0) jd += ipart((275 * month) / 9.0) jd += day jd += 1729777 - 2400000.5 # Return 240000.5 as first part of JD. jd -= 0.5 # Convert midday to midnight. return MJD_0, jd def jd2jcal(jd1, jd2): """Julian calendar date for the given Julian date. The input and output are for the proleptic Julian calendar, i.e., no consideration of historical usage of the calendar is made. Parameters ---------- jd1, jd2: int Sum of the two numbers is taken as the given Julian date. For example `jd1` can be the zero point of MJD (MJD_0) and `jd2` can be the MJD of the date and time. But any combination will work. Returns ------- y, m, d, f : int, int, int, float Four element tuple containing year, month, day and the fractional part of the day in the Julian calendar. The first three are integers, and the last part is a float. Examples -------- >>> jd2jcal(*jcal2jd(2000, 1, 1)) (2000, 1, 1, 0.0) >>> jd2jcal(*jcal2jd(-4000, 10, 11)) (-4000, 10, 11, 0.0) >>> jcal2jd(2000, 1, 1) (2400000.5, 51557.0) >>> jd2jcal(2400000.5, 51557.0) (2000, 1, 1, 0.0) >>> jd2jcal(2400000.5, 51557.5) (2000, 1, 1, 0.5) >>> jd2jcal(2400000.5, 51557.245) (2000, 1, 1, 0.24500000000261934) >>> jd2jcal(2400000.5, 51557.1) (2000, 1, 1, 0.099999999998544808) >>> jd2jcal(2400000.5, 51557.75) (2000, 1, 1, 0.75) """ from math import modf jd1_f, jd1_i = modf(jd1) jd2_f, jd2_i = modf(jd2) jd_i = jd1_i + jd2_i f = jd1_f + jd2_f # Set JD to noon of the current date. Fractional part is the # fraction from midnight of the current date. if -0.5 < f < 0.5: f += 0.5 elif f >= 0.5: jd_i += 1 f -= 0.5 elif f <= -0.5: jd_i -= 1 f += 1.5 j = jd_i + 1402.0 k = ipart((j - 1) / 1461.0) l = j - (1461.0 * k) n = ipart((l - 1) / 365.0) - ipart(l / 1461.0) i = l - (365.0 * n) + 30.0 j = ipart((80.0 * i) / 2447.0) day = i - ipart((2447.0 * j) / 80.0) i = ipart(j / 11.0) month = j + 2 - (12.0 * i) year = (4 * k) + n + i - 4716.0 return int(year), int(month), int(day), f # Some tests. def _test_gcal2jd_with_sla_cldj(): """Compare gcal2jd with slalib.sla_cldj.""" import random try: from pyslalib import slalib except ImportError: print("SLALIB (PySLALIB not available).") return 1 n = 1000 mday = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] # sla_cldj needs year > -4699 i.e., 4700 BC. year = [random.randint(-4699, 2200) for i in range(n)] month = [random.randint(1, 12) for i in range(n)] day = [random.randint(1, 31) for i in range(n)] for i in range(n): x = 0 if is_leap(year[i]) and month[i] == 2: x = 1 if day[i] > mday[month[i]] + x: day[i] = mday[month[i]] jd_jdc = [gcal2jd(y, m, d)[1] for y, m, d in zip(year, month, day)] jd_sla = [slalib.sla_cldj(y, m, d)[0] for y, m, d in zip(year, month, day)] diff = [abs(i - j) for i, j in zip(jd_sla, jd_jdc)] assert max(diff) <= 1e-8 assert min(diff) <= 1e-8 def _test_jd2gcal(): """Check jd2gcal as reverse of gcal2jd.""" import random n = 1000 mday = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] year = [random.randint(-4699, 2200) for i in range(n)] month = [random.randint(1, 12) for i in range(n)] day = [random.randint(1, 31) for i in range(n)] for i in range(n): x = 0 if is_leap(year[i]) and month[i] == 2: x = 1 if day[i] > mday[month[i]] + x: day[i] = mday[month[i]] jd = [gcal2jd(y, m, d)[1] for y, m, d in zip(year, month, day)] x = [jd2gcal(MJD_0, i) for i in jd] for i in range(n): assert x[i][0] == year[i] assert x[i][1] == month[i] assert x[i][2] == day[i] assert x[i][3] <= 1e-15 def _test_jd2jcal(): """Check jd2jcal as reverse of jcal2jd.""" import random n = 1000 year = [random.randint(-4699, 2200) for i in range(n)] month = [random.randint(1, 12) for i in range(n)] day = [random.randint(1, 28) for i in range(n)] jd = [jcal2jd(y, m, d)[1] for y, m, d in zip(year, month, day)] x = [jd2gcal(MJD_0, i) for i in jd] for i in range(n): assert x[i][0] == year[i] assert x[i][1] == month[i] assert x[i][2] == day[i] assert x[i][3] <= 1e-15 jdcal-1.0/setup.py000066400000000000000000000014201164377237700141570ustar00rootroot00000000000000#!/usr/bin/env python from distutils.core import setup import jdcal version = jdcal.__version__ long_description = open("README.rst").read() setup( name="jdcal", version=version, description="Julian dates from proleptic Gregorian and Julian calendars.", long_description=long_description, license='BSD', author="Prasanth Nair", author_email="prasanthhn@gmail.com", url='http://github.com/phn/jdcal', classifiers=[ 'Development Status :: 6 - Mature', 'Intended Audience :: Science/Research', 'Operating System :: OS Independent', 'License :: OSI Approved :: BSD License', 'Topic :: Scientific/Engineering :: Astronomy', 'Programming Language :: Python', ], py_modules=["jdcal"] )