Closed
Description
xref #12585
I think this ought to raise a ValueErrror:
In [1]: pd.to_datetime('01-13-2012', dayfirst=True)
Out[1]: datetime.datetime(2012, 1, 13, 0, 0)
This means if my data is bad (i.e. somehow I have a mixture of american and british string-dates), I won't be told there was an issue when parsing! I can't think of a usecase where this kind of precedence would be appropriate, and it means you'll end up with incorrect dates.
The precedence behaviour appears to be a feature from dateutil (which tslib.array_to_datetime calls):
In [2]: from dateutil.parser import parse as parse_date
In [3]: parse_date('1/12/2012', dayfirst=True)
Out[3]: datetime.datetime(2012, 12, 1, 0, 0)
In [4]: parse_date('1/13/2012', dayfirst=True)
Out[4]: datetime.datetime(2012, 1, 13, 0, 0)
It should raising like this:
In [5]: parse_date('14/14/2012', dayfirst=True)
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-5-ca14fc16e421> in <module>()
----> 1 parse_date('14/14/2012', dayfirst=True)
/Library/Python/2.7/site-packages/dateutil/parser.pyc in parse(timestr, parserinfo, **kwargs)
718 return parser(parserinfo).parse(timestr, **kwargs)
719 else:
--> 720 return DEFAULTPARSER.parse(timestr, **kwargs)
721
722
/Library/Python/2.7/site-packages/dateutil/parser.pyc in parse(self, timestr, default, ignoretz, tzinfos, **kwargs)
315 if value is not None:
316 repl[attr] = value
--> 317 ret = default.replace(**repl)
318 if res.weekday is not None and not res.day:
319 ret = ret+relativedelta.relativedelta(weekday=res.weekday)
ValueError: month must be in 1..12
... :(