python - Pandas loc 给了我 keyerror，索引是日期

Question

我有这个包含 EOD 股票价格的数据集

                YAR.OL     NHY.OL  ...      DNB.OL     SBO.OL
date                               ...                       
1986-03-13         NaN        NaN  ...         NaN        NaN
1986-03-14         NaN        NaN  ...         NaN        NaN
1986-03-17         NaN        NaN  ...         NaN        NaN
1986-03-18         NaN        NaN  ...         NaN        NaN
1986-03-19         NaN        NaN  ...         NaN        NaN
...                ...        ...  ...         ...        ...
2020-07-24  377.799988  26.740000  ...  144.500000  51.000000
2020-07-27  381.799988  26.350000  ...  142.199997  50.599998
2020-07-28  382.399994  26.490000  ...  142.000000  50.200001
2020-07-29  377.899994  26.389999  ...  142.100006  50.799999
2020-07-30  372.000000  25.049999  ...  137.149994  49.799999

索引是日期。但是，当我尝试做

df.loc[['2020-07-29']]

我收到一条错误消息：KeyError: '2010-07-29'

或者当我这样做时：

df.loc[['2010-06-29']]

我得到KeyError：“[Index(['2010-06-29'], dtype='object', name='date')] 中没有一个在 [index] 中”

我在打印 df.index 时检查了索引，并且该值确实存在。

Index([1986-03-13, 1986-03-14, 1986-03-17, 1986-03-18, 1986-03-19, 1986-03-20,
       1986-03-21, 1986-03-24, 1986-03-25, 1986-03-26,
       ...
       2020-07-17, 2020-07-20, 2020-07-21, 2020-07-22, 2020-07-23, 2020-07-24,
       2020-07-27, 2020-07-28, 2020-07-29, 2020-07-30],
      dtype='object', name='date', length=8667)

有谁知道为什么会这样？

标签： pythonpandas

Answer 1

让我们将索引的 dtype 更改为 datetime 以为您的数据框创建 DateTimeIndex。

df.index = pd.to_datetime(df.index)

现在，让我们使用df.loc['2010-07-29'].