from __future__ import absolute_import
from __future__ import division
# Copyright (c) 2010-2017 openpyxl
"""Manage Excel date weirdness."""
# Python stdlib imports
import datetime
from datetime import timedelta, tzinfo
from math import isnan
import re
from jdcal import (
gcal2jd,
jd2gcal,
MJD_0
)
# constants
MAC_EPOCH = datetime.date(1904, 1, 1)
WINDOWS_EPOCH = datetime.date(1899, 12, 30)
CALENDAR_WINDOWS_1900 = sum(gcal2jd(WINDOWS_EPOCH.year, WINDOWS_EPOCH.month, WINDOWS_EPOCH.day))
CALENDAR_MAC_1904 = sum(gcal2jd(MAC_EPOCH.year, MAC_EPOCH.month, MAC_EPOCH.day))
SECS_PER_DAY = 86400
EPOCH = datetime.datetime.utcfromtimestamp(0)
W3CDTF_FORMAT = '%Y-%m-%dT%H:%M:%SZ'
W3CDTF_REGEX = re.compile('(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2})(.(\d{2}))?Z?')
[docs]def datetime_to_W3CDTF(dt):
"""Convert from a datetime to a timestamp string."""
return datetime.datetime.strftime(dt, W3CDTF_FORMAT)
[docs]def W3CDTF_to_datetime(formatted_string):
"""Convert from a timestamp string to a datetime object."""
match = W3CDTF_REGEX.match(formatted_string)
dt = [int(v) for v in match.groups()[:6]]
return datetime.datetime(*dt)
[docs]def to_excel(dt, offset=CALENDAR_WINDOWS_1900):
if isnan(dt.year): # Pandas supports Not a Date
return
jul = sum(gcal2jd(dt.year, dt.month, dt.day)) - offset
if jul <= 60 and offset == CALENDAR_WINDOWS_1900:
jul -= 1
if hasattr(dt, 'time'):
jul += time_to_days(dt)
return jul
[docs]def from_excel(value, offset=CALENDAR_WINDOWS_1900):
if value is None:
return
if 1 < value < 60 and offset == CALENDAR_WINDOWS_1900:
value += 1
parts = list(jd2gcal(MJD_0, value + offset - MJD_0))
_, fraction = divmod(value, 1)
jumped = (parts[-1] == 0 and fraction > 0)
diff = datetime.timedelta(days=fraction)
if 0 < abs(value) < 1:
return days_to_time(diff)
if not jumped:
return datetime.datetime(*parts[:3]) + diff
else:
return datetime.datetime(*parts[:3] + [0])
[docs]class GMT(tzinfo):
[docs] def utcoffset(self, dt):
return timedelta(0)
[docs] def dst(self, dt):
return timedelta(0)
[docs] def tzname(self,dt):
return "GMT"
try:
from datetime import timezone
UTC = timezone(timedelta(0))
except ImportError:
# Python 2.6
UTC = GMT()
[docs]def time_to_days(value):
"""Convert a time value to fractions of day"""
if value.tzinfo is not None:
value = value.astimezone(UTC)
return (
(value.hour * 3600)
+ (value.minute * 60)
+ value.second
+ value.microsecond / 10**6
) / SECS_PER_DAY
[docs]def timedelta_to_days(value):
"""Convert a timedelta value to fractions of a day"""
if not hasattr(value, 'total_seconds'):
secs = (value.microseconds +
(value.seconds + value.days * SECS_PER_DAY) * 10**6) / 10**6
else:
secs =value.total_seconds()
return secs / SECS_PER_DAY
[docs]def days_to_time(value):
mins, seconds = divmod(value.seconds, 60)
hours, mins = divmod(mins, 60)
return datetime.time(hours, mins, seconds, value.microseconds)