My tools of the trade for python programming.
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# $Id:,v 1.1 2011-09-01 15:34:03 wirawan Exp $
# wpylib.datetime
# Created: 20110901
# Wirawan Purwanto
Frequently used date/time related tools.
Do not confuse this with python's core datetime module, which
is not being replaced by this module!
import sys
import time
def date8():
"""Returns a standard 8-digit representation of the current date."""
return time.strftime("%Y%m%d")
def time_diff(time1, time2):
"""Returns the time difference (time1 - time2) in seconds."""
from time import mktime
return mktime(time1) - mktime(time2)
def shift_time(t, dt, localtime=True):
"""Shifts a time data by an amount in dt (specified in seconds)."""
if isinstance(t, time.struct_time):
t1 = time.mktime(t) + dt
t1 = t + dt
if localtime:
return time.localtime(t1)
return time.gmtime(t1)
class utime_to_iso_proc(object):
"""Converts UNIX time (seconds since Epoch) to ISO-formatted time string.
In order to ease time computation/conversion,
we will use numeric TZ shift (+/-HH:MM) instead of
letter TZ code (EDT, EST, GMT, etc).
The full ISO-8601 format is like this:
* YYYY-MM-DD = year, month, date
* hh:mm:ss.fff = hour, minute, second, fraction of the second
* AA:BB = time shift due to time zone
But some variants are valid:
* YYYY-MM-DD hh:mm (GNU ls timestyle 'long-iso')
* YYYY-MM-DD +AA:BB (GNU ls timestyle 'full-iso')
There are some built-in formats in this subroutine.
They can be tweaked further (adding new formats is OK; but changing
existing ones are not recommended).
The format string will undergo two passes:
* first pass, via strftime
* second pass, if '%' still exists in the string, expansion using 'opts'
computed variables.
Identifiers for second pass must be named, and must use '%%(NAME)s' kind of
format with double percent sign.
* (subheading "Time Strings")
map_fmt_iso = {
0: "%Y-%m-%d %H:%M:%S %%(TZ)s", # original default of this routine
'default': "%Y-%m-%d %H:%M:%S %%(TZ)s", # original default of this routine
# Global formats
'iso8601': "%Y-%m-%dT%H:%M:%S.%%(NANOSECS)s%%(ZTZ)s", # formal ISO-8601
# GNU-specific formats
'gnu long-iso': "%Y-%m-%d %H:%M",
'gnu full-iso': "%Y-%m-%d %H:%M:%S.%%(NANOSECS)s %%(TZ)s",
# My custom formats
'idtstamp': "%Y-%m-%dT%H:%M:%S.%%(MILLISECS)s",
def __init__(self, fmt=0):
from copy import copy
# Make a copy so we don't clobber the original class:
self.map_fmt_iso = copy(self.map_fmt_iso)
self.fmt = fmt
def __call__(self, t=None, local=True, fmt=None):
from time import time, localtime, gmtime, strftime, timezone
if fmt == None: fmt = self.fmt
if t == None:
t = time()
# The time, the nanosecond part:
t_ns = int((t - int(t)) * 1e+9)
opts = {
'NANOSECS': ("%09.0f" % t_ns),
'MICROSECS': ("%06.0f" % (t_ns // 1000)),
'MILLISECS': ("%03.0f" % (t_ns // 1000000)),
if local:
tt = localtime(t)
# dtz = Delta time due to Time Zone
dtz = -timezone + tt.tm_isdst * 3600
# hopefully dtz is divisible by 60
# It would be silly for a gov't to make its time
# differ by seconds to GMT!
dsec = abs(dtz) % 60
dmin = abs(dtz // 60) % 60
dhr = dtz // 3600
if dsec == 00:
opts['TZ'] = "%+03d:%02d" % (dhr, dmin)
optz['TZ'] = "%+03d:%02d:%02d" % (dhr, dmin, dsec)
opts['ZTZ'] = opts['TZ']
tt = gmtime(t)
opts['TZ'] = "+00:00"
opts['ZTZ'] = "Z"
# Numeric timezone offset is created by hand
# because I don't want to use %Z, nor do I want to use
# "%z" (which did not work in python)
fmt = self.map_fmt_iso.get(fmt, fmt)
rslt1 = strftime(fmt, tt)
if "%" in rslt1:
rslt2 = rslt1 % opts
return rslt2
return rslt1
utime_to_iso = utime_to_iso_proc()