def to_datetime(arg, errors='raise', dayfirst=False, yearfirst=False, utc=None, box=True, format=None, exact=True, unit=None, infer_datetime_format=False, origin='unix', cache=False): """ Convert argument to datetime. Parameters ---------- arg : integer, float, string, datetime, list, tuple, 1-d array, Series .. versionadded:: 0.18.1 or DataFrame/dict-like errors : {'ignore', 'raise', 'coerce'}, default 'raise' - If 'raise', then invalid parsing will raise an exception - If 'coerce', then invalid parsing will be set as NaT - If 'ignore', then invalid parsing will return the input dayfirst : boolean, default False Specify a date parse order if `arg` is str or its list-likes. If True, parses dates with the day first, eg 10/11/12 is parsed as 2012-11-10. Warning: dayfirst=True is not strict, but will prefer to parse with day first (this is a known bug, based on dateutil behavior). yearfirst : boolean, default False Specify a date parse order if `arg` is str or its list-likes. - If True parses dates with the year first, eg 10/11/12 is parsed as 2010-11-12. - If both dayfirst and yearfirst are True, yearfirst is preceded (same as dateutil). Warning: yearfirst=True is not strict, but will prefer to parse with year first (this is a known bug, based on dateutil beahavior). .. versionadded:: 0.16.1 utc : boolean, default None Return UTC DatetimeIndex if True (converting any tz-aware datetime.datetime objects as well). box : boolean, default True - If True returns a DatetimeIndex - If False returns ndarray of values. format : string, default None strftime to parse time, eg "%d/%m/%Y", note that "%f" will parse all the way up to nanoseconds. exact : boolean, True by default - If True, require an exact format match. - If False, allow the format to match anywhere in the target string. unit : string, default 'ns' unit of the arg (D,s,ms,us,ns) denote the unit, which is an integer or float number. This will be based off the origin. Example, with unit='ms' and origin='unix' (the default), this would calculate the number of milliseconds to the unix epoch start. infer_datetime_format : boolean, default False If True and no `format` is given, attempt to infer the format of the datetime strings, and if it can be inferred, switch to a faster method of parsing them. In some cases this can increase the parsing speed by ~5-10x. origin : scalar, default is 'unix' Define the reference date. The numeric values would be parsed as number of units (defined by `unit`) since this reference date. - If 'unix' (or POSIX) time; origin is set to 1970-01-01. - If 'julian', unit must be 'D', and origin is set to beginning of Julian Calendar. Julian day number 0 is assigned to the day starting at noon on January 1, 4713 BC. - If Timestamp convertible, origin is set to Timestamp identified by origin. .. versionadded:: 0.20.0 cache : boolean, default False If True, use a cache of unique, converted dates to apply the datetime conversion. May produce sigificant speed-up when parsing duplicate date strings, especially ones with timezone offsets. .. versionadded:: 0.22.0 Returns ------- ret : datetime if parsing succeeded. Return type depends on input: - list-like: DatetimeIndex - Series: Series of datetime64 dtype - scalar: Timestamp In case when it is not possible to return designated types (e.g. when any element of input is before Timestamp.min or after Timestamp.max) return will have datetime.datetime type (or correspoding array/Series). Examples -------- Assembling a datetime from multiple columns of a DataFrame. The keys can be common abbreviations like ['year', 'month', 'day', 'minute', 'second', 'ms', 'us', 'ns']) or plurals of the same >>> df = pd.DataFrame({'year': [2015, 2016], 'month': [2, 3], 'day': [4, 5]}) >>> pd.to_datetime(df) 0 2015-02-04 1 2016-03-05 dtype: datetime64[ns] If a date does not meet the `timestamp limitations <http://pandas.pydata.org/pandas-docs/stable/timeseries.html #timeseries-timestamp-limits>`_, passing errors='ignore' will return the original input instead of raising any exception. Passing errors='coerce' will force an out-of-bounds date to NaT, in addition to forcing non-dates (or non-parseable dates) to NaT. >>> pd.to_datetime('13000101', format='%Y%m%d', errors='ignore') datetime.datetime(1300, 1, 1, 0, 0) >>> pd.to_datetime('13000101', format='%Y%m%d', errors='coerce') NaT Passing infer_datetime_format=True can often-times speedup a parsing if its not an ISO8601 format exactly, but in a regular format. >>> s = pd.Series(['3/11/2000', '3/12/2000', '3/13/2000']*1000) >>> s.head() 0 3/11/2000 1 3/12/2000 2 3/13/2000 3 3/11/2000 4 3/12/2000 dtype: object >>> %timeit pd.to_datetime(s,infer_datetime_format=True) 100 loops, best of 3: 10.4 ms per loop >>> %timeit pd.to_datetime(s,infer_datetime_format=False) 1 loop, best of 3: 471 ms per loop Using a unix epoch time >>> pd.to_datetime(1490195805, unit='s') Timestamp('2017-03-22 15:16:45') >>> pd.to_datetime(1490195805433502912, unit='ns') Timestamp('2017-03-22 15:16:45.433502912') .. warning:: For float arg, precision rounding might happen. To prevent unexpected behavior use a fixed-width exact type. Using a non-unix epoch origin >>> pd.to_datetime([1, 2, 3], unit='D', origin=pd.Timestamp('1960-01-01')) 0 1960-01-02 1 1960-01-03 2 1960-01-04 See also -------- pandas.DataFrame.astype : Cast argument to a specified dtype. pandas.to_timedelta : Convert argument to timedelta. """ from pandas.core.indexes.datetimes import DatetimeIndex tz = 'utc' if utc else None def _convert_listlike(arg, box, format, name=None, tz=tz): if isinstance(arg, (list, tuple)): arg = np.array(arg, dtype='O') # these are shortcutable if is_datetime64tz_dtype(arg): if not isinstance(arg, DatetimeIndex): return DatetimeIndex(arg, tz=tz, name=name) if utc: arg = arg.tz_convert(None).tz_localize('UTC') return arg elif is_datetime64_ns_dtype(arg): if box and not isinstance(arg, DatetimeIndex): try: return DatetimeIndex(arg, tz=tz, name=name) except ValueError: pass return arg elif unit is not None: if format is not None: raise ValueError("cannot specify both format and unit") arg = getattr(arg, 'values', arg) result = tslib.array_with_unit_to_datetime(arg, unit, errors=errors) if box: if errors == 'ignore': from pandas import Index return Index(result) return DatetimeIndex(result, tz=tz, name=name) return result elif getattr(arg, 'ndim', 1) > 1: raise TypeError('arg must be a string, datetime, list, tuple, ' '1-d array, or Series') arg = _ensure_object(arg) require_iso8601 = False if infer_datetime_format and format is None: format = _guess_datetime_format_for_array(arg, dayfirst=dayfirst) if format is not None: # There is a special fast-path for iso8601 formatted # datetime strings, so in those cases don't use the inferred # format because this path makes process slower in this # special case format_is_iso8601 = _format_is_iso(format) if format_is_iso8601: require_iso8601 = not infer_datetime_format format = None try: result = None if format is not None: # shortcut formatting here if format == '%Y%m%d': try: result = _attempt_YYYYMMDD(arg, errors=errors) except: raise ValueError("cannot convert the input to " "'%Y%m%d' date format") # fallback if result is None: try: result = array_strptime(arg, format, exact=exact, errors=errors) except tslib.OutOfBoundsDatetime: if errors == 'raise': raise result = arg except ValueError: # if format was inferred, try falling back # to array_to_datetime - terminate here # for specified formats if not infer_datetime_format: if errors == 'raise': raise result = arg if result is None and (format is None or infer_datetime_format): result = tslib.array_to_datetime( arg, errors=errors, utc=utc, dayfirst=dayfirst, yearfirst=yearfirst, require_iso8601=require_iso8601 ) if is_datetime64_dtype(result) and box: result = DatetimeIndex(result, tz=tz, name=name) return result except ValueError as e: try: values, tz = conversion.datetime_to_datetime64(arg) return DatetimeIndex._simple_new(values, name=name, tz=tz) except (ValueError, TypeError): raise e if arg is None: return None # handle origin if origin == 'julian': original = arg j0 = tslib.Timestamp(0).to_julian_date() if unit != 'D': raise ValueError("unit must be 'D' for origin='julian'") try: arg = arg - j0 except: raise ValueError("incompatible 'arg' type for given " "'origin'='julian'") # premptively check this for a nice range j_max = tslib.Timestamp.max.to_julian_date() - j0 j_min = tslib.Timestamp.min.to_julian_date() - j0 if np.any(arg > j_max) or np.any(arg < j_min): raise tslib.OutOfBoundsDatetime( "{original} is Out of Bounds for " "origin='julian'".format(original=original)) elif origin not in ['unix', 'julian']: # arg must be a numeric original = arg if not ((is_scalar(arg) and (is_integer(arg) or is_float(arg))) or is_numeric_dtype(np.asarray(arg))): raise ValueError( "'{arg}' is not compatible with origin='{origin}'; " "it must be numeric with a unit specified ".format( arg=arg, origin=origin)) # we are going to offset back to unix / epoch time try: offset = tslib.Timestamp(origin) except tslib.OutOfBoundsDatetime: raise tslib.OutOfBoundsDatetime( "origin {origin} is Out of Bounds".format(origin=origin)) except ValueError: raise ValueError("origin {origin} cannot be converted " "to a Timestamp".format(origin=origin)) if offset.tz is not None: raise ValueError( "origin offset {} must be tz-naive".format(offset)) offset -= tslib.Timestamp(0) # convert the offset to the unit of the arg # this should be lossless in terms of precision offset = offset // tslib.Timedelta(1, unit=unit) # scalars & ndarray-like can handle the addition if is_list_like(arg) and not isinstance( arg, (ABCSeries, ABCIndexClass, np.ndarray)): arg = np.asarray(arg) arg = arg + offset if isinstance(arg, tslib.Timestamp): result = arg elif isinstance(arg, ABCSeries): cache_array = _maybe_cache(arg, format, cache, tz, _convert_listlike) if not cache_array.empty: result = arg.map(cache_array) else: from pandas import Series values = _convert_listlike(arg._values, True, format) result = Series(values, index=arg.index, name=arg.name) elif isinstance(arg, (ABCDataFrame, MutableMapping)): result = _assemble_from_unit_mappings(arg, errors=errors) elif isinstance(arg, ABCIndexClass): cache_array = _maybe_cache(arg, format, cache, tz, _convert_listlike) if not cache_array.empty: result = _convert_and_box_cache(arg, cache_array, box, errors, name=arg.name) else: result = _convert_listlike(arg, box, format, name=arg.name) elif is_list_like(arg): cache_array = _maybe_cache(arg, format, cache, tz, _convert_listlike) if not cache_array.empty: result = _convert_and_box_cache(arg, cache_array, box, errors) else: result = _convert_listlike(arg, box, format) else: result = _convert_listlike(np.array([arg]), box, format)[0] return result
def _adjust_to_origin(arg, origin, unit): """ Helper function for to_datetime. Adjust input argument to the specified origin Parameters ---------- arg : list, tuple, ndarray, Series, Index date to be adjusted origin : 'julian' or Timestamp origin offset for the arg unit : string passed unit from to_datetime, must be 'D' Returns ------- ndarray or scalar of adjusted date(s) """ if origin == 'julian': original = arg j0 = tslib.Timestamp(0).to_julian_date() if unit != 'D': raise ValueError("unit must be 'D' for origin='julian'") try: arg = arg - j0 except: raise ValueError("incompatible 'arg' type for given " "'origin'='julian'") # premptively check this for a nice range j_max = tslib.Timestamp.max.to_julian_date() - j0 j_min = tslib.Timestamp.min.to_julian_date() - j0 if np.any(arg > j_max) or np.any(arg < j_min): raise tslib.OutOfBoundsDatetime( "{original} is Out of Bounds for " "origin='julian'".format(original=original)) else: # arg must be numeric if not ((is_scalar(arg) and (is_integer(arg) or is_float(arg))) or is_numeric_dtype(np.asarray(arg))): raise ValueError( "'{arg}' is not compatible with origin='{origin}'; " "it must be numeric with a unit specified ".format( arg=arg, origin=origin)) # we are going to offset back to unix / epoch time try: offset = tslib.Timestamp(origin) except tslib.OutOfBoundsDatetime: raise tslib.OutOfBoundsDatetime( "origin {origin} is Out of Bounds".format(origin=origin)) except ValueError: raise ValueError("origin {origin} cannot be converted " "to a Timestamp".format(origin=origin)) if offset.tz is not None: raise ValueError( "origin offset {} must be tz-naive".format(offset)) offset -= tslib.Timestamp(0) # convert the offset to the unit of the arg # this should be lossless in terms of precision offset = offset // tslib.Timedelta(1, unit=unit) # scalars & ndarray-like can handle the addition if is_list_like(arg) and not isinstance( arg, (ABCSeries, ABCIndexClass, np.ndarray)): arg = np.asarray(arg) arg = arg + offset return arg