""" Parsing functions for datetime and datetime-like strings. """ import re import time from libc.string cimport strchr import cython from cython import Py_ssize_t from cpython.datetime cimport ( datetime, datetime_new, import_datetime, tzinfo, ) from cpython.object cimport PyObject_Str from cpython.version cimport PY_VERSION_HEX import_datetime() import numpy as np cimport numpy as cnp from numpy cimport ( PyArray_GETITEM, PyArray_ITER_DATA, PyArray_ITER_NEXT, PyArray_IterNew, flatiter, float64_t, ) cnp.import_array() # dateutil compat from dateutil.parser import ( DEFAULTPARSER, parse as du_parse, ) from dateutil.relativedelta import relativedelta from dateutil.tz import ( tzlocal as _dateutil_tzlocal, tzoffset, tzstr as _dateutil_tzstr, tzutc as _dateutil_tzutc, ) from pandas._config import get_option from pandas._libs.tslibs.ccalendar cimport c_MONTH_NUMBERS from pandas._libs.tslibs.nattype cimport ( c_NaT as NaT, c_nat_strings as nat_strings, ) from pandas._libs.tslibs.offsets cimport is_offset_object from pandas._libs.tslibs.util cimport ( get_c_string_buf_and_size, is_array, ) cdef extern from "../src/headers/portable.h": int getdigit_ascii(char c, int default) nogil cdef extern from "../src/parser/tokenizer.h": double xstrtod(const char *p, char **q, char decimal, char sci, char tsep, int skip_trailing, int *error, int *maybe_int) # ---------------------------------------------------------------------- # Constants class DateParseError(ValueError): pass _DEFAULT_DATETIME = datetime(1, 1, 1).replace(hour=0, minute=0, second=0, microsecond=0) cdef: set _not_datelike_strings = {'a', 'A', 'm', 'M', 'p', 'P', 't', 'T'} # ---------------------------------------------------------------------- cdef: const char* delimiters = " /-." int MAX_DAYS_IN_MONTH = 31, MAX_MONTH = 12 cdef inline bint _is_not_delimiter(const char ch): return strchr(delimiters, ch) == NULL cdef inline int _parse_2digit(const char* s): cdef int result = 0 result += getdigit_ascii(s[0], -10) * 10 result += getdigit_ascii(s[1], -100) * 1 return result cdef inline int _parse_4digit(const char* s): cdef int result = 0 result += getdigit_ascii(s[0], -10) * 1000 result += getdigit_ascii(s[1], -100) * 100 result += getdigit_ascii(s[2], -1000) * 10 result += getdigit_ascii(s[3], -10000) * 1 return result cdef inline object _parse_delimited_date(str date_string, bint dayfirst): """ Parse special cases of dates: MM/DD/YYYY, DD/MM/YYYY, MM/YYYY. At the beginning function tries to parse date in MM/DD/YYYY format, but if month > 12 - in DD/MM/YYYY (`dayfirst == False`). With `dayfirst == True` function makes an attempt to parse date in DD/MM/YYYY, if an attempt is wrong - in DD/MM/YYYY For MM/DD/YYYY, DD/MM/YYYY: delimiter can be a space or one of /-. For MM/YYYY: delimiter can be a space or one of /- If `date_string` can't be converted to date, then function returns None, None Parameters ---------- date_string : str dayfirst : bool Returns: -------- datetime or None str or None Describing resolution of the parsed string. """ cdef: const char* buf Py_ssize_t length int day = 1, month = 1, year bint can_swap = 0 buf = get_c_string_buf_and_size(date_string, &length) if length == 10: # parsing MM?DD?YYYY and DD?MM?YYYY dates if _is_not_delimiter(buf[2]) or _is_not_delimiter(buf[5]): return None, None month = _parse_2digit(buf) day = _parse_2digit(buf + 3) year = _parse_4digit(buf + 6) reso = 'day' can_swap = 1 elif length == 7: # parsing MM?YYYY dates if buf[2] == b'.' or _is_not_delimiter(buf[2]): # we cannot reliably tell whether e.g. 10.2010 is a float # or a date, thus we refuse to parse it here return None, None month = _parse_2digit(buf) year = _parse_4digit(buf + 3) reso = 'month' else: return None, None if month < 0 or day < 0 or year < 1000: # some part is not an integer, so # date_string can't be converted to date, above format return None, None if 1 <= month <= MAX_DAYS_IN_MONTH and 1 <= day <= MAX_DAYS_IN_MONTH \ and (month <= MAX_MONTH or day <= MAX_MONTH): if (month > MAX_MONTH or (day <= MAX_MONTH and dayfirst)) and can_swap: day, month = month, day if PY_VERSION_HEX >= 0x03060100: # In Python <= 3.6.0 there is no range checking for invalid dates # in C api, thus we call faster C version for 3.6.1 or newer return datetime_new(year, month, day, 0, 0, 0, 0, None), reso return datetime(year, month, day, 0, 0, 0, 0, None), reso raise DateParseError(f"Invalid date specified ({month}/{day})") cdef inline bint does_string_look_like_time(str parse_string): """ Checks whether given string is a time: it has to start either from H:MM or from HH:MM, and hour and minute values must be valid. Parameters ---------- parse_string : str Returns: -------- bool Whether given string is potentially a time. """ cdef: const char* buf Py_ssize_t length int hour = -1, minute = -1 buf = get_c_string_buf_and_size(parse_string, &length) if length >= 4: if buf[1] == b':': # h:MM format hour = getdigit_ascii(buf[0], -1) minute = _parse_2digit(buf + 2) elif buf[2] == b':': # HH:MM format hour = _parse_2digit(buf) minute = _parse_2digit(buf + 3) return 0 <= hour <= 23 and 0 <= minute <= 59 def parse_datetime_string( str date_string, bint dayfirst=False, bint yearfirst=False, **kwargs, ) -> datetime: """ Parse datetime string, only returns datetime. Also cares special handling matching time patterns. Returns ------- datetime """ cdef: object dt if not _does_string_look_like_datetime(date_string): raise ValueError('Given date string not likely a datetime.') if does_string_look_like_time(date_string): # use current datetime as default, not pass _DEFAULT_DATETIME dt = du_parse(date_string, dayfirst=dayfirst, yearfirst=yearfirst, **kwargs) return dt dt, _ = _parse_delimited_date(date_string, dayfirst) if dt is not None: return dt try: dt, _ = _parse_dateabbr_string(date_string, _DEFAULT_DATETIME, freq=None) return dt except DateParseError: raise except ValueError: pass try: dt = du_parse(date_string, default=_DEFAULT_DATETIME, dayfirst=dayfirst, yearfirst=yearfirst, **kwargs) except TypeError: # following may be raised from dateutil # TypeError: 'NoneType' object is not iterable raise ValueError('Given date string not likely a datetime.') return dt def parse_time_string(arg: str, freq=None, dayfirst=None, yearfirst=None): """ Try hard to parse datetime string, leveraging dateutil plus some extra goodies like quarter recognition. Parameters ---------- arg : str freq : str or DateOffset, default None Helps with interpreting time string if supplied dayfirst : bool, default None If None uses default from print_config yearfirst : bool, default None If None uses default from print_config Returns ------- datetime str Describing resolution of parsed string. """ if is_offset_object(freq): freq = freq.rule_code if dayfirst is None or yearfirst is None: if dayfirst is None: dayfirst = get_option("display.date_dayfirst") if yearfirst is None: yearfirst = get_option("display.date_yearfirst") res = parse_datetime_string_with_reso(arg, freq=freq, dayfirst=dayfirst, yearfirst=yearfirst) return res cdef parse_datetime_string_with_reso( str date_string, str freq=None, bint dayfirst=False, bint yearfirst=False, ): """ Parse datetime string and try to identify its resolution. Returns ------- datetime str Inferred resolution of the parsed string. Raises ------ ValueError : preliminary check suggests string is not datetime DateParseError : error within dateutil """ cdef: object parsed, reso if not _does_string_look_like_datetime(date_string): raise ValueError('Given date string not likely a datetime.') parsed, reso = _parse_delimited_date(date_string, dayfirst) if parsed is not None: return parsed, reso try: return _parse_dateabbr_string(date_string, _DEFAULT_DATETIME, freq) except DateParseError: raise except ValueError: pass try: parsed, reso = dateutil_parse(date_string, _DEFAULT_DATETIME, dayfirst=dayfirst, yearfirst=yearfirst, ignoretz=False, tzinfos=None) except (ValueError, OverflowError) as err: # TODO: allow raise of errors within instead raise DateParseError(err) if parsed is None: raise DateParseError(f"Could not parse {date_string}") return parsed, reso cpdef bint _does_string_look_like_datetime(str py_string): """ Checks whether given string is a datetime: it has to start with '0' or be greater than 1000. Parameters ---------- py_string: str Returns ------- bool Whether given string is potentially a datetime. """ cdef: const char *buf char *endptr = NULL Py_ssize_t length = -1 double converted_date char first int error = 0 buf = get_c_string_buf_and_size(py_string, &length) if length >= 1: first = buf[0] if first == b'0': # Strings starting with 0 are more consistent with a # date-like string than a number return True elif py_string in _not_datelike_strings: return False else: # xstrtod with such parameters copies behavior of python `float` # cast; for example, " 35.e-1 " is valid string for this cast so, # for correctly xstrtod call necessary to pass these params: # b'.' - a dot is used as separator, b'e' - an exponential form of # a float number can be used, b'\0' - not to use a thousand # separator, 1 - skip extra spaces before and after, converted_date = xstrtod(buf, &endptr, b'.', b'e', b'\0', 1, &error, NULL) # if there were no errors and the whole line was parsed, then ... if error == 0 and endptr == buf + length: return converted_date >= 1000 return True cdef inline object _parse_dateabbr_string(object date_string, datetime default, str freq=None): cdef: object ret # year initialized to prevent compiler warnings int year = -1, quarter = -1, month, mnum, date_len # special handling for possibilities eg, 2Q2005, 2Q05, 2005Q1, 05Q1 assert isinstance(date_string, str) if date_string in nat_strings: return NaT, '' date_string = date_string.upper() date_len = len(date_string) if date_len == 4: # parse year only like 2000 try: ret = default.replace(year=int(date_string)) return ret, 'year' except ValueError: pass try: if 4 <= date_len <= 7: i = date_string.index('Q', 1, 6) if i == 1: quarter = int(date_string[0]) if date_len == 4 or (date_len == 5 and date_string[i + 1] == '-'): # r'(\d)Q-?(\d\d)') year = 2000 + int(date_string[-2:]) elif date_len == 6 or (date_len == 7 and date_string[i + 1] == '-'): # r'(\d)Q-?(\d\d\d\d)') year = int(date_string[-4:]) else: raise ValueError elif i == 2 or i == 3: # r'(\d\d)-?Q(\d)' if date_len == 4 or (date_len == 5 and date_string[i - 1] == '-'): quarter = int(date_string[-1]) year = 2000 + int(date_string[:2]) else: raise ValueError elif i == 4 or i == 5: if date_len == 6 or (date_len == 7 and date_string[i - 1] == '-'): # r'(\d\d\d\d)-?Q(\d)' quarter = int(date_string[-1]) year = int(date_string[:4]) else: raise ValueError if not (1 <= quarter <= 4): raise DateParseError(f'Incorrect quarterly string is given, ' f'quarter must be ' f'between 1 and 4: {date_string}') try: # GH#1228 year, month = quarter_to_myear(year, quarter, freq) except KeyError: raise DateParseError("Unable to retrieve month " "information from given " f"freq: {freq}") ret = default.replace(year=year, month=month) return ret, 'quarter' except DateParseError: raise except ValueError: pass if date_len == 6 and (freq == 'M' or getattr(freq, 'rule_code', None) == 'M'): year = int(date_string[:4]) month = int(date_string[4:6]) try: ret = default.replace(year=year, month=month) return ret, 'month' except ValueError: pass for pat in ['%Y-%m', '%b %Y', '%b-%Y']: try: ret = datetime.strptime(date_string, pat) return ret, 'month' except ValueError: pass raise ValueError(f'Unable to parse {date_string}') cpdef quarter_to_myear(int year, int quarter, str freq): """ A quarterly frequency defines a "year" which may not coincide with the calendar-year. Find the calendar-year and calendar-month associated with the given year and quarter under the `freq`-derived calendar. Parameters ---------- year : int quarter : int freq : str or None Returns ------- year : int month : int See Also -------- Period.qyear """ if quarter <= 0 or quarter > 4: raise ValueError("Quarter must be 1 <= q <= 4") if freq is not None: mnum = c_MONTH_NUMBERS[get_rule_month(freq)] + 1 month = (mnum + (quarter - 1) * 3) % 12 + 1 if month > mnum: year -= 1 else: month = (quarter - 1) * 3 + 1 return year, month cdef dateutil_parse( str timestr, object default, bint ignoretz=False, object tzinfos=None, bint dayfirst=False, bint yearfirst=False, ): """ lifted from dateutil to get resolution""" cdef: object res, attr, ret, tzdata object reso = None dict repl = {} res, _ = DEFAULTPARSER._parse(timestr, dayfirst=dayfirst, yearfirst=yearfirst) if res is None: raise ValueError(f"Unknown datetime string format, unable to parse: {timestr}") for attr in ["year", "month", "day", "hour", "minute", "second", "microsecond"]: value = getattr(res, attr) if value is not None: repl[attr] = value reso = attr if reso is None: raise ValueError(f"Unable to parse datetime string: {timestr}") if reso == 'microsecond': if repl['microsecond'] == 0: reso = 'second' elif repl['microsecond'] % 1000 == 0: reso = 'millisecond' ret = default.replace(**repl) if res.weekday is not None and not res.day: ret = ret + relativedelta.relativedelta(weekday=res.weekday) if not ignoretz: if callable(tzinfos) or tzinfos and res.tzname in tzinfos: # Note: as of 1.0 this is not reached because # we never pass tzinfos, see GH#22234 if callable(tzinfos): tzdata = tzinfos(res.tzname, res.tzoffset) else: tzdata = tzinfos.get(res.tzname) if isinstance(tzdata, tzinfo): new_tzinfo = tzdata elif isinstance(tzdata, str): new_tzinfo = _dateutil_tzstr(tzdata) elif isinstance(tzdata, int): new_tzinfo = tzoffset(res.tzname, tzdata) else: raise ValueError("offset must be tzinfo subclass, " "tz string, or int offset") ret = ret.replace(tzinfo=new_tzinfo) elif res.tzname and res.tzname in time.tzname: ret = ret.replace(tzinfo=_dateutil_tzlocal()) elif res.tzoffset == 0: ret = ret.replace(tzinfo=_dateutil_tzutc()) elif res.tzoffset: ret = ret.replace(tzinfo=tzoffset(res.tzname, res.tzoffset)) return ret, reso # ---------------------------------------------------------------------- # Parsing for type-inference def try_parse_dates( object[:] values, parser=None, bint dayfirst=False, default=None, ) -> np.ndarray: cdef: Py_ssize_t i, n object[:] result n = len(values) result = np.empty(n, dtype='O') if parser is None: if default is None: # GH2618 date = datetime.now() default = datetime(date.year, date.month, 1) parse_date = lambda x: du_parse(x, dayfirst=dayfirst, default=default) # EAFP here try: for i in range(n): if values[i] == '': result[i] = np.nan else: result[i] = parse_date(values[i]) except Exception: # Since parser is user-defined, we can't guess what it might raise return values else: parse_date = parser for i in range(n): if values[i] == '': result[i] = np.nan else: result[i] = parse_date(values[i]) return result.base # .base to access underlying ndarray def try_parse_date_and_time( object[:] dates, object[:] times, date_parser=None, time_parser=None, bint dayfirst=False, default=None, ) -> np.ndarray: cdef: Py_ssize_t i, n object[:] result n = len(dates) # TODO(cython 3.0): Use len instead of `shape[0]` if times.shape[0] != n: raise ValueError('Length of dates and times must be equal') result = np.empty(n, dtype='O') if date_parser is None: if default is None: # GH2618 date = datetime.now() default = datetime(date.year, date.month, 1) parse_date = lambda x: du_parse(x, dayfirst=dayfirst, default=default) else: parse_date = date_parser if time_parser is None: parse_time = lambda x: du_parse(x) else: parse_time = time_parser for i in range(n): d = parse_date(str(dates[i])) t = parse_time(str(times[i])) result[i] = datetime(d.year, d.month, d.day, t.hour, t.minute, t.second) return result.base # .base to access underlying ndarray def try_parse_year_month_day( object[:] years, object[:] months, object[:] days ) -> np.ndarray: cdef: Py_ssize_t i, n object[:] result n = len(years) # TODO(cython 3.0): Use len instead of `shape[0]` if months.shape[0] != n or days.shape[0] != n: raise ValueError('Length of years/months/days must all be equal') result = np.empty(n, dtype='O') for i in range(n): result[i] = datetime(int(years[i]), int(months[i]), int(days[i])) return result.base # .base to access underlying ndarray def try_parse_datetime_components(object[:] years, object[:] months, object[:] days, object[:] hours, object[:] minutes, object[:] seconds) -> np.ndarray: cdef: Py_ssize_t i, n object[:] result int secs double float_secs double micros n = len(years) # TODO(cython 3.0): Use len instead of `shape[0]` if ( months.shape[0] != n or days.shape[0] != n or hours.shape[0] != n or minutes.shape[0] != n or seconds.shape[0] != n ): raise ValueError('Length of all datetime components must be equal') result = np.empty(n, dtype='O') for i in range(n): float_secs = float(seconds[i]) secs = int(float_secs) micros = float_secs - secs if micros > 0: micros = micros * 1000000 result[i] = datetime(int(years[i]), int(months[i]), int(days[i]), int(hours[i]), int(minutes[i]), secs, int(micros)) return result.base # .base to access underlying ndarray # ---------------------------------------------------------------------- # Miscellaneous # Class copied verbatim from https://github.com/dateutil/dateutil/pull/732 # # We use this class to parse and tokenize date strings. However, as it is # a private class in the dateutil library, relying on backwards compatibility # is not practical. In fact, using this class issues warnings (xref gh-21322). # Thus, we port the class over so that both issues are resolved. # # Copyright (c) 2017 - dateutil contributors class _timelex: def __init__(self, instream): if getattr(instream, 'decode', None) is not None: instream = instream.decode() if isinstance(instream, str): self.stream = instream elif getattr(instream, 'read', None) is None: raise TypeError( 'Parser must be a string or character stream, not ' f'{type(instream).__name__}') else: self.stream = instream.read() def get_tokens(self): """ This function breaks the time string into lexical units (tokens), which can be parsed by the parser. Lexical units are demarcated by changes in the character set, so any continuous string of letters is considered one unit, any continuous string of numbers is considered one unit. The main complication arises from the fact that dots ('.') can be used both as separators (e.g. "Sep.20.2009") or decimal points (e.g. "4:30:21.447"). As such, it is necessary to read the full context of any dot-separated strings before breaking it into tokens; as such, this function maintains a "token stack", for when the ambiguous context demands that multiple tokens be parsed at once. """ cdef: Py_ssize_t n stream = self.stream.replace('\x00', '') # TODO: Change \s --> \s+ (this doesn't match existing behavior) # TODO: change the punctuation block to punc+ (does not match existing) # TODO: can we merge the two digit patterns? tokens = re.findall('\s|' '(? bint: """ Does format match the iso8601 set that can be handled by the C parser? Generally of form YYYY-MM-DDTHH:MM:SS - date separator can be different but must be consistent. Leading 0s in dates and times are optional. """ iso_template = '%Y{date_sep}%m{date_sep}%d{time_sep}%H:%M:%S.%f'.format excluded_formats = ['%Y%m%d', '%Y%m', '%Y'] for date_sep in [' ', '/', '\\', '-', '.', '']: for time_sep in [' ', 'T']: if (iso_template(date_sep=date_sep, time_sep=time_sep ).startswith(f) and f not in excluded_formats): return True return False def guess_datetime_format( dt_str, bint dayfirst=False, dt_str_parse=du_parse, dt_str_split=_DATEUTIL_LEXER_SPLIT, ): """ Guess the datetime format of a given datetime string. Parameters ---------- dt_str : str Datetime string to guess the format of. dayfirst : bool, default False If True parses dates with the day first, eg 20/01/2005 Warning: dayfirst=True is not strict, but will prefer to parse with day first (this is a known bug). dt_str_parse : function, defaults to `dateutil.parser.parse` This function should take in a datetime string and return a `datetime.datetime` guess that the datetime string represents dt_str_split : function, defaults to `_DATEUTIL_LEXER_SPLIT` (dateutil) This function should take in a datetime string and return a list of strings, the guess of the various specific parts e.g. '2011/12/30' -> ['2011', '/', '12', '/', '30'] Returns ------- ret : datetime format string (for `strftime` or `strptime`) """ if dt_str_parse is None or dt_str_split is None: return None if not isinstance(dt_str, str): return None day_attribute_and_format = (('day',), '%d', 2) # attr name, format, padding (if any) datetime_attrs_to_format = [ (('year', 'month', 'day'), '%Y%m%d', 0), (('year',), '%Y', 0), (('month',), '%B', 0), (('month',), '%b', 0), (('month',), '%m', 2), day_attribute_and_format, (('hour',), '%H', 2), (('minute',), '%M', 2), (('second',), '%S', 2), (('microsecond',), '%f', 6), (('second', 'microsecond'), '%S.%f', 0), (('tzinfo',), '%Z', 0), ] if dayfirst: datetime_attrs_to_format.remove(day_attribute_and_format) datetime_attrs_to_format.insert(0, day_attribute_and_format) try: parsed_datetime = dt_str_parse(dt_str, dayfirst=dayfirst) except (ValueError, OverflowError): # In case the datetime can't be parsed, its format cannot be guessed return None if parsed_datetime is None: return None # the default dt_str_split from dateutil will never raise here; we assume # that any user-provided function will not either. tokens = dt_str_split(dt_str) format_guess = [None] * len(tokens) found_attrs = set() for attrs, attr_format, padding in datetime_attrs_to_format: # If a given attribute has been placed in the format string, skip # over other formats for that same underlying attribute (IE, month # can be represented in multiple different ways) if set(attrs) & found_attrs: continue if all(getattr(parsed_datetime, attr) is not None for attr in attrs): for i, token_format in enumerate(format_guess): token_filled = tokens[i].zfill(padding) if (token_format is None and token_filled == parsed_datetime.strftime(attr_format)): format_guess[i] = attr_format tokens[i] = token_filled found_attrs.update(attrs) break # Only consider it a valid guess if we have a year, month and day if len({'year', 'month', 'day'} & found_attrs) != 3: return None output_format = [] for i, guess in enumerate(format_guess): if guess is not None: # Either fill in the format placeholder (like %Y) output_format.append(guess) else: # Or just the token separate (IE, the dashes in "01-01-2013") try: # If the token is numeric, then we likely didn't parse it # properly, so our guess is wrong float(tokens[i]) return None except ValueError: pass output_format.append(tokens[i]) guessed_format = ''.join(output_format) # rebuild string, capturing any inferred padding dt_str = ''.join(tokens) if parsed_datetime.strftime(guessed_format) == dt_str: return guessed_format else: return None @cython.wraparound(False) @cython.boundscheck(False) cdef inline object convert_to_unicode(object item, bint keep_trivial_numbers): """ Convert `item` to str. Parameters ---------- item : object keep_trivial_numbers : bool if True, then conversion (to string from integer/float zero) is not performed Returns ------- str or int or float """ cdef: float64_t float_item if keep_trivial_numbers: if isinstance(item, int): if item == 0: return item elif isinstance(item, float): float_item = item if float_item == 0.0 or float_item != float_item: return item if not isinstance(item, str): item = PyObject_Str(item) return item @cython.wraparound(False) @cython.boundscheck(False) def concat_date_cols(tuple date_cols, bint keep_trivial_numbers=True) -> np.ndarray: """ Concatenates elements from numpy arrays in `date_cols` into strings. Parameters ---------- date_cols : tuple[ndarray] keep_trivial_numbers : bool, default True if True and len(date_cols) == 1, then conversion (to string from integer/float zero) is not performed Returns ------- arr_of_rows : ndarray[object] Examples -------- >>> dates=np.array(['3/31/2019', '4/31/2019'], dtype=object) >>> times=np.array(['11:20', '10:45'], dtype=object) >>> result = concat_date_cols((dates, times)) >>> result array(['3/31/2019 11:20', '4/31/2019 10:45'], dtype=object) """ cdef: Py_ssize_t rows_count = 0, col_count = len(date_cols) Py_ssize_t col_idx, row_idx list list_to_join cnp.ndarray[object] iters object[::1] iters_view flatiter it cnp.ndarray[object] result object[:] result_view if col_count == 0: return np.zeros(0, dtype=object) if not all(is_array(array) for array in date_cols): raise ValueError("not all elements from date_cols are numpy arrays") rows_count = min(len(array) for array in date_cols) result = np.zeros(rows_count, dtype=object) result_view = result if col_count == 1: array = date_cols[0] it = PyArray_IterNew(array) for row_idx in range(rows_count): item = PyArray_GETITEM(array, PyArray_ITER_DATA(it)) result_view[row_idx] = convert_to_unicode(item, keep_trivial_numbers) PyArray_ITER_NEXT(it) else: # create fixed size list - more efficient memory allocation list_to_join = [None] * col_count iters = np.zeros(col_count, dtype=object) # create memoryview of iters ndarray, that will contain some # flatiter's for each array in `date_cols` - more efficient indexing iters_view = iters for col_idx, array in enumerate(date_cols): iters_view[col_idx] = PyArray_IterNew(array) # array elements that are on the same line are converted to one string for row_idx in range(rows_count): for col_idx, array in enumerate(date_cols): # this cast is needed, because we did not find a way # to efficiently store `flatiter` type objects in ndarray it = iters_view[col_idx] item = PyArray_GETITEM(array, PyArray_ITER_DATA(it)) list_to_join[col_idx] = convert_to_unicode(item, False) PyArray_ITER_NEXT(it) result_view[row_idx] = " ".join(list_to_join) return result cpdef str get_rule_month(str source): """ Return starting month of given freq, default is December. Parameters ---------- source : str Derived from `freq.rule_code` or `freq.freqstr`. Returns ------- rule_month: str Examples -------- >>> get_rule_month('D') 'DEC' >>> get_rule_month('A-JAN') 'JAN' """ source = source.upper() if "-" not in source: return "DEC" else: return source.split("-")[1]