pandas Sqlite 和重新采样错误仅对 DatetimeIndex 有效

Question

我正在尝试使用 pandas 和 sqlite 将数据读入数据帧。我认为如果我从 CSV 文件中读取数据，这段重新采样为每小时平均值的代码是有效的，但我不确定为什么是从 Sqlite 读取？抱歉，我对数据库知之甚少，非常感谢任何提示。如果我运行下面的代码，我可以打印第一个 df 但重新采样错误：import pandas as pdfrom sqlalchemy import create_engineimport sqlite3con = sqlite3.connect('./save_data.db')df = pd.read_sql("SELECT * from all_data", con, index_col='Date', parse_dates=True)df.set_index('Date')print(df)hourly_avg['kW'] = df['kW'].resample('H').mean()print('hourly_avg.kW', hourly_avg.kW)输出：>>> === RESTART: C:\Users\Desktop\tester\Test.py ===                            Date         kW0     2020-10-08 12:23:30.968967  68.1299971     2020-10-08 12:25:39.375298  68.1299972     2020-10-08 12:26:52.939991  68.1299973     2020-10-08 12:27:57.839540  68.1299974     2020-10-08 12:29:02.382524  68.129997...                          ...        ...1917  2020-10-09 10:14:35.113254  68.1499941918  2020-10-09 10:15:08.840759  68.1899951919  2020-10-09 10:15:41.873328  68.2499921920  2020-10-09 10:16:14.953312  68.2899931921  2020-10-09 10:16:48.043465  68.289993[1922 rows x 2 columns]Traceback (most recent call last):  File "C:\Users\Desktop\tester\Test.py", line 11, in <module>    hourly_avg['kW'] = df['kW'].resample('H').mean()  File "C:\Users\AppData\Local\Programs\Python\Python37\lib\site-packages\pandas\core\generic.py", line 8087, in resample    offset=offset,  File "C:\Users\AppData\Local\Programs\Python\Python37\lib\site-packages\pandas\core\resample.py", line 1269, in get_resampler    return tg._get_resampler(obj, kind=kind)  File "C:\Users\AppData\Local\Programs\Python\Python37\lib\site-packages\pandas\core\resample.py", line 1435, in _get_resampler    "Only valid with DatetimeIndex, "TypeError: Only valid with DatetimeIndex, TimedeltaIndex or PeriodIndex, but got an instance of 'RangeIndex'>>> 

Answer 1

你需要使用 aDatetimeindex但你忘记了inplace=True

尝试这个：

df.set_index('Date', inplace=True)

而不是这个：

df.set_index('Date')

这应该可以解决它。