Timestamp('now', tz=xxx) result wrong

[zhopan77]

In earlier version (0.14 and earlier), Timestamp('now', tz=xxx) will return time now in xxx time zone.

In 0.15.1, it returns the time in UTC but tagged with xxx time zone.

Example:

In version 0.12.0:

import pandas
pandas.version.version
'0.12.0'
pandas.Timestamp('now', tz='US/Central')
Timestamp('2014-12-04 12:06:03-0600', tz='US/Central')
pandas.Timestamp('now')
Timestamp('2014-12-04 18:06:11', tz=None)

In version 0.15.1:

import pandas
pandas.version.version
'0.15.1'
pandas.Timestamp('now', tz='US/Central')
Timestamp('2014-12-04 18:07:29-0600', tz='US/Central')
pandas.Timestamp('now')
Timestamp('2014-12-04 18:07:37')

[jreback]

this should return exactly what datetime.now(tz) returns. https://docs.python.org/2/library/datetime.html#datetime-objects

In [10]: import pytz

In [11]: tz = pytz.timezone('US/Eastern')

In [12]: tz
Out[12]: <DstTzInfo 'US/Eastern' LMT-1 day, 19:04:00 STD>

In [13]: datetime.now()
Out[13]: datetime.datetime(2014, 12, 4, 18, 27, 9, 211050)

In [14]: Timestamp.now()
Out[14]: Timestamp('2014-12-04 18:27:11.883002')

In [15]: datetime.now(tz)
Out[15]: datetime.datetime(2014, 12, 4, 18, 27, 15, 514437, tzinfo=<DstTzInfo 'US/Eastern' EST-1 day, 19:00:00 STD>)

In [16]: Timestamp.now(tz)
Out[16]: Timestamp('2014-12-04 18:27:20.778796-0500', tz='US/Eastern')

In [17]: Timestamp(datetime.now(tz))
Out[17]: Timestamp('2014-12-04 18:28:17.047905-0500', tz='US/Eastern')

looks correct to me (and IIRC 0.12 was wrong)

[rockg]

I think the issue is with Timestamp('now') which I didn't even know was a possibility.

Timestamp.now()
Out[7]: Timestamp('2014-12-04 20:57:54.425729')
Timestamp('now')
Out[8]: Timestamp('2014-12-05 01:58:39')

[rockg]

See here: https://github.com/pydata/pandas/blob/master/pandas/src/datetime/np_datetime_strings.c#L457

[jreback]

from pandas/src/numpy_datetime_strings.c

is where this is parsed. So that's a UTC time, which is then has a tz tacked on. I think this needs to indicate is UTC when passed back

 * Parses (almost) standard ISO 8601 date strings. The differences are:
 *
 * + The date "20100312" is parsed as the year 20100312, not as
 *   equivalent to "2010-03-12". The '-' in the dates are not optional.
 * + Only seconds may have a decimal point, with up to 18 digits after it
 *   (maximum attoseconds precision).
 * + Either a 'T' as in ISO 8601 or a ' ' may be used to separate
 *   the date and the time. Both are treated equivalently.
 * + Doesn't (yet) handle the "YYYY-DDD" or "YYYY-Www" formats.
 * + Doesn't handle leap seconds (seconds value has 60 in these cases).
 * + Doesn't handle 24:00:00 as synonym for midnight (00:00:00) tomorrow
 * + Accepts special values "NaT" (not a time), "Today", (current
 *   day according to local time) and "Now" (current time in UTC).

[rockg]

I certainly think that we should change the behavior of 'now' to be consistent with .now. It doesn't make sense to be different. Agreed?

[jreback]

yep