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將Pandas列轉換爲數據幀

2017-10-13 234 views
2

我有一個名爲'Date'的熊貓數據幀列，其格式爲：'％Y％m％d％H％M％H％M'（第一個％H％M是當地時間&第二個％H％M是UTC）。將Pandas列轉換爲數據幀

我想將其轉換爲格式：％Y-％m-％d_％H％M（保持UTC％H％M）。

obs_df = pd.read_csv(obs, names= ['WBAN','Date','Extinc Coeff', 'D/N', 'Dir 2min av wind', 
           'Spd 2min av wind(kts)', 'Dir max 5min av wind','Spd_max_5min_av_wind(kts)', 
           'Constant','Runway vis range'], usecols= ['WBAN', 'Date', 
                     'Spd_max_5min_av_wind(kts)'], 
       na_filter=False)

這裏的數據框的樣子：

   Date WBAN Spd_max_5min_av_wind(kts) 
0 2014100108481348 KACK 19 
1 2014100108491349 KACK 18 
2 2014100108501350 KACK 20 
3 2014100108511351 KACK 19 
4 2014100108521352 KACK 17

這裏就是我已經試過：

import datetime as dt 

obs_df['Date'] = obs_df['Date'].apply(lambda x: dt.datetime.strptime(x, '%Y%m%d%H%M%H%M'))

和

obs_df['Date'] = pd.to_datetime(obs_df['Date'], format = '%Y%m%d%H%M%H%M')

這是我得到的錯誤對於這兩種嘗試：

--------------------------------------------------------------------------- 
error          Traceback (most recent call last) 
<ipython-input-200-27e83cc1348d> in <module>() 
----> 1 obs_df['Date'] = obs_df['Date'].apply(lambda x: dt.datetime.strptime(x, '%Y%m%d%H%M%H%M')) 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/pandas/core/series.py in apply(self, func, convert_dtype, args, **kwds) 
    2353    else: 
    2354     values = self.asobject 
-> 2355     mapped = lib.map_infer(values, f, convert=convert_dtype) 
    2356 
    2357   if len(mapped) and isinstance(mapped[0], Series): 

pandas/_libs/src/inference.pyx in pandas._libs.lib.map_infer (pandas/_libs/lib.c:66645)() 

<ipython-input-200-27e83cc1348d> in <lambda>(x) 
----> 1 obs_df['Date'] = obs_df['Date'].apply(lambda x: dt.datetime.strptime(x, '%Y%m%d%H%M%H%M')) 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/_strptime.py in _strptime_datetime(cls, data_string, format) 
    498  """Return a class cls instance based on the input string and the 
    499  format string.""" 
--> 500  tt, fraction = _strptime(data_string, format) 
    501  tzname, gmtoff = tt[-2:] 
    502  args = tt[:6] + (fraction,) 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/_strptime.py in _strptime(data_string, format) 
    318   if not format_regex: 
    319    try: 
--> 320     format_regex = _TimeRE_cache.compile(format) 
    321    # KeyError raised when a bad format is found; can be specified as 
    322    # \\, in which case it was a stray % but with a space after it 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/_strptime.py in compile(self, format) 
    266  def compile(self, format): 
    267   """Return a compiled re object for the format string.""" 
--> 268   return re_compile(self.pattern(format), IGNORECASE) 
    269 
    270 _cache_lock = _thread_allocate_lock() 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/re.py in compile(pattern, flags) 
    222 def compile(pattern, flags=0): 
    223  "Compile a regular expression pattern, returning a pattern object." 
--> 224  return _compile(pattern, flags) 
    225 
    226 def purge(): 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/re.py in _compile(pattern, flags) 
    291  if not sre_compile.isstring(pattern): 
    292   raise TypeError("first argument must be string or compiled pattern") 
--> 293  p = sre_compile.compile(pattern, flags) 
    294  if not (flags & DEBUG): 
    295   if len(_cache) >= _MAXCACHE: 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/sre_compile.py in compile(p, flags) 
    534  if isstring(p): 
    535   pattern = p 
--> 536   p = sre_parse.parse(p, flags) 
    537  else: 
    538   pattern = None 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/sre_parse.py in parse(str, flags, pattern) 
    827  pattern.str = str 
    828 
--> 829  p = _parse_sub(source, pattern, 0) 
    830  p.pattern.flags = fix_flags(str, p.pattern.flags) 
    831 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/sre_parse.py in _parse_sub(source, state, nested) 
    435  start = source.tell() 
    436  while True: 
--> 437   itemsappend(_parse(source, state)) 
    438   if not sourcematch("|"): 
    439    break 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/sre_parse.py in _parse(source, state) 
    772      group = state.opengroup(name) 
    773     except error as err: 
--> 774      raise source.error(err.msg, len(name) + 1) from None 
    775    if condgroup: 
    776     p = _parse_sub_cond(source, state, condgroup) 

error: redefinition of group name 'H' as group 6; was group 4 at position 127

我嘗試這樣做，以及：

obs_df['Date'] = pd.to_datetime(obs_df['Date'], errors='raise', yearfirst=True, utc=True, box=False, format="%Y-%m-%d_%H%M", exact=False, 
          infer_datetime_format=True)

但得到這個錯誤：

--------------------------------------------------------------------------- 
ValueError        Traceback (most recent call last) 
pandas/_libs/tslib.pyx in pandas._libs.tslib.array_to_datetime (pandas/_libs/tslib.c:44294)() 

pandas/_libs/src/datetime.pxd in datetime._string_to_dts (pandas/_libs/tslib.c:98425)() 

ValueError: Error parsing datetime string "2014100108481348" at position 8 

During handling of the above exception, another exception occurred: 

OverflowError        Traceback (most recent call last) 
pandas/_libs/tslib.pyx in pandas._libs.tslib.array_to_datetime (pandas/_libs/tslib.c:44703)() 

pandas/_libs/tslib.pyx in pandas._libs.tslib.parse_datetime_string (pandas/_libs/tslib.c:35351)() 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/dateutil/parser.py in parse(timestr, parserinfo, **kwargs) 
    1181  else: 
-> 1182   return DEFAULTPARSER.parse(timestr, **kwargs) 
    1183 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/dateutil/parser.py in parse(self, timestr, default, ignoretz, tzinfos, **kwargs) 
    577 
--> 578    if cday > monthrange(cyear, cmonth)[1]: 
    579     repl['day'] = monthrange(cyear, cmonth)[1] 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/calendar.py in monthrange(year, month) 
    120   raise IllegalMonthError(month) 
--> 121  day1 = weekday(year, month, 1) 
    122  ndays = mdays[month] + (month == February and isleap(year)) 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/calendar.py in weekday(year, month, day) 
    112  day (1-31).""" 
--> 113  return datetime.date(year, month, day).weekday() 
    114 

OverflowError: signed integer is greater than maximum 

During handling of the above exception, another exception occurred: 

TypeError         Traceback (most recent call last) 
pandas/_libs/tslib.pyx in pandas._libs.tslib.array_to_datetime (pandas/_libs/tslib.c:44803)() 

TypeError: invalid string coercion to datetime 

During handling of the above exception, another exception occurred: 

OverflowError        Traceback (most recent call last) 
<ipython-input-205-5e9ed01bf0eb> in <module>() 
     1 obs_df['Date'] = pd.to_datetime(obs_df['Date'], errors='raise', yearfirst=True, utc=True, box=False, format="%Y-%m-%d_%H%M", exact=False, 
----> 2         infer_datetime_format=True) 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/pandas/core/tools/datetimes.py in to_datetime(arg, errors, dayfirst, yearfirst, utc, box, format, exact, unit, infer_datetime_format, origin) 
    507  elif isinstance(arg, ABCSeries): 
    508   from pandas import Series 
--> 509   values = _convert_listlike(arg._values, False, format) 
    510   result = Series(values, index=arg.index, name=arg.name) 
    511  elif isinstance(arg, (ABCDataFrame, MutableMapping)): 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/pandas/core/tools/datetimes.py in _convert_listlike(arg, box, format, name, tz) 
    433      dayfirst=dayfirst, 
    434      yearfirst=yearfirst, 
--> 435      require_iso8601=require_iso8601 
    436    ) 
    437 

pandas/_libs/tslib.pyx in pandas._libs.tslib.array_to_datetime (pandas/_libs/tslib.c:46617)() 

pandas/_libs/tslib.pyx in pandas._libs.tslib.array_to_datetime (pandas/_libs/tslib.c:46233)() 

pandas/_libs/tslib.pyx in pandas._libs.tslib.array_to_datetime (pandas/_libs/tslib.c:46122)() 

pandas/_libs/tslib.pyx in pandas._libs.tslib.parse_datetime_string (pandas/_libs/tslib.c:35351)() 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/dateutil/parser.py in parse(timestr, parserinfo, **kwargs) 
    1180   return parser(parserinfo).parse(timestr, **kwargs) 
    1181  else: 
-> 1182   return DEFAULTPARSER.parse(timestr, **kwargs) 
    1183 
    1184 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/dateutil/parser.py in parse(self, timestr, default, ignoretz, tzinfos, **kwargs) 
    576    cday = default.day if res.day is None else res.day 
    577 
--> 578    if cday > monthrange(cyear, cmonth)[1]: 
    579     repl['day'] = monthrange(cyear, cmonth)[1] 
    580 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/calendar.py in monthrange(year, month) 
    119  if not 1 <= month <= 12: 
    120   raise IllegalMonthError(month) 
--> 121  day1 = weekday(year, month, 1) 
    122  ndays = mdays[month] + (month == February and isleap(year)) 
    123  return day1, ndays 

/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/calendar.py in weekday(year, month, day) 
    111  """Return weekday (0-6 ~ Mon-Sun) for year (1970-...), month (1-12), 
    112  day (1-31).""" 
--> 113  return datetime.date(year, month, day).weekday() 
    114 
    115 

OverflowError: signed integer is greater than maximum

正如你所知道的，我還沒有試過加連字符和下劃線，因爲這可能需要另一個步驟，但任何指導將不勝感激。

來源

2017-10-13 mosesheavy

回答

1

使用format='%Y%m%d%H%M%S%f'

In [1454]: pd.to_datetime(df.Date, format='%Y%m%d%H%M%S%f') 
Out[1454]: 
0 2014-10-01 08:48:13.480 
1 2014-10-01 08:49:13.490 
2 2014-10-01 08:50:13.500 
3 2014-10-01 08:51:13.510 
4 2014-10-01 08:52:13.520 
Name: Date, dtype: datetime64[ns]

而且，圓其關閉，以分鐘，如果需要的。

In [1462]: pd.to_datetime(df.Date, format='%Y%m%d%H%M%S%f').dt.round('60S') 
Out[1462]: 
0 2014-10-01 08:48:00 
1 2014-10-01 08:49:00 
2 2014-10-01 08:50:00 
3 2014-10-01 08:51:00 
4 2014-10-01 08:52:00 
Name: Date, dtype: datetime64[ns]

詳細

In [1455]: df 
Out[1455]: 
       Date WBAN Spd_max_5min_av_wind(kts) 
0 2014100108481348 KACK       19 
1 2014100108491349 KACK       18 
2 2014100108501350 KACK       20 
3 2014100108511351 KACK       19 
4 2014100108521352 KACK       17

來源

2017-10-13 06:09:03 Zero

1

，我認爲是不可能的使用UTC與另一個時間，所以刪除最後4個號碼僅UTC日期時間：

obs_df['Date'] = pd.to_datetime(obs_df['Date'].astype(str).str[:-4], format = '%Y%m%d%H%M') 
print (obs_df) 
       Date WBAN Spd_max_5min_av_wind(kts) 
0 2014-10-01 08:48:00 KACK       19 
1 2014-10-01 08:49:00 KACK       18 
2 2014-10-01 08:50:00 KACK       20 
3 2014-10-01 08:51:00 KACK       19 
4 2014-10-01 08:52:00 KACK       17

或者，如果只需要另一個日期時間與最後%H%M：

d = obs_df['Date'].astype(str) 
d = d.str[:8] + d.str[-4:] 
print (d) 
0 201410011348 
1 201410011349 
2 201410011350 
3 201410011351 
4 201410011352 
Name: Date, dtype: object 

obs_df['Date'] = pd.to_datetime(d, format = '%Y%m%d%H%M') 
print (obs_df) 
       Date WBAN Spd_max_5min_av_wind(kts) 
0 2014-10-01 13:48:00 KACK       19 
1 2014-10-01 13:49:00 KACK       18 
2 2014-10-01 13:50:00 KACK       20 
3 2014-10-01 13:51:00 KACK       19 
4 2014-10-01 13:52:00 KACK       17

解時區：

import pytz 

#find offset as difference of hours form first date 
a = str(obs_df.loc[0, 'Date']) 
offset = (int(a[12:14]) - int(a[8:10])) * 60 
print (offset) 
300 

obs_df['Date'] = pd.to_datetime(obs_df['Date'].astype(str).str[:-4], format = '%Y%m%d%H%M') 
print (obs_df) 
       Date WBAN Spd_max_5min_av_wind(kts) 
0 2014-10-01 08:48:00 KACK       19 
1 2014-10-01 08:49:00 KACK       18 
2 2014-10-01 08:50:00 KACK       20 
3 2014-10-01 08:51:00 KACK       19 
4 2014-10-01 08:52:00 KACK       17

首先tz_localize然後tz_convert由偏移：

obs_df['Date'] = obs_df['Date'].dt.tz_localize('UTC').dt.tz_convert(pytz.FixedOffset(offset)) 
print (obs_df) 
         Date WBAN Spd_max_5min_av_wind(kts) 
0 2014-10-01 13:48:00+05:00 KACK       19 
1 2014-10-01 13:49:00+05:00 KACK       18 
2 2014-10-01 13:50:00+05:00 KACK       20 
3 2014-10-01 13:51:00+05:00 KACK       19 
4 2014-10-01 13:52:00+05:00 KACK       17

更多信息here。

來源

2017-10-13 06:10:20 jezrael

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