添加最后一行代码会导致此错误：“in get_loc raise KeyError(key) from err”。 是什么导致了这个错误？

Question

我正在尝试将日期从 2013 年到 2018 年进行子集化，并添加代码的最后一行代码会导致此错误Error 。

为什么会发生这种情况，谁能告诉我是否有更好的方法来对日期进行子集化？

错误：

File "C:\Users\Dev\AppData\Local\Programs\Python\Python39\lib\site-packages\pandas\core\indexes\base.py", line 3080, in get_loc
    return self._engine.get_loc(casted_key)
  File "pandas\_libs\index.pyx", line 70, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\index.pyx", line 101, in pandas._libs.index.IndexEngine.get_loc
  File "pandas\_libs\hashtable_class_helper.pxi", line 4554, in pandas._libs.hashtable.PyObjectHashTable.get_item
  File "pandas\_libs\hashtable_class_helper.pxi", line 4562, in pandas._libs.hashtable.PyObjectHashTable.get_item
KeyError: 'Date'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "D:\Python Projects\MTE\Fitness Tracker\Analyze Your Runkeeper Fitness Data\datasets\Fitness Data.py", line 29, in <module>
    datesss=df_run[(df_run['Date'] > '01-01-2013') & (df_run['Date'] <= '31-12-2018')]
  File "C:\Users\Dev\AppData\Local\Programs\Python\Python39\lib\site-packages\pandas\core\frame.py", line 3024, in __getitem__
    indexer = self.columns.get_loc(key)
  File "C:\Users\Dev\AppData\Local\Programs\Python\Python39\lib\site-packages\pandas\core\indexes\base.py", line 3082, in get_loc
    raise KeyError(key) from err
KeyError: 'Date'

Answer 1

您的代码看起来正确，您能否检查一下您何时从 df_activities 创建 df_run Dataframe，它具有“日期”列而不是索引，否则您将不得不重置索引（）。

错误表明 DataFrame(df_run) 要么不包含“日期”列，要么被设置为索引。

可以使用 Boolean 掩码，日期为 object 类型或时间戳类型：

解决方案

mask = (df['Date'] > '01-01-2013') & (df['Date'] <= '31-12-2019')
df.loc[mask]