我在将 pandas DataFrame 索引从整数更改为日期时间时遇到问题。我想这样做，以便我可以调用 reindex 并填写表中列出的日期之间的日期。请注意，我现在必须使用 pandas 0.7.3，因为我也在使用 qstk，而 qstk 依赖于 pandas 0.7.3
首先，这是我的布局：
(Pdb) df
AAPL GOOG IBM XOM date
1 0 0 4000 0 2011-01-13 16:00:00
2 0 1000 4000 0 2011-01-26 16:00:00
3 0 1000 4000 0 2011-02-02 16:00:00
4 0 1000 4000 4000 2011-02-10 16:00:00
6 0 0 1800 4000 2011-03-03 16:00:00
7 0 0 3300 4000 2011-06-03 16:00:00
8 0 0 0 4000 2011-05-03 16:00:00
9 1200 0 0 4000 2011-06-10 16:00:00
11 1200 0 0 4000 2011-08-01 16:00:00
12 0 0 0 4000 2011-12-20 16:00:00
(Pdb) type(df['date'])
<class 'pandas.core.series.Series'>
(Pdb) df2 = DataFrame(index=df['date'])
(Pdb) df2
Empty DataFrame
Columns: array([], dtype=object)
Index: array([2011-01-13 16:00:00, 2011-01-26 16:00:00, 2011-02-02 16:00:00,
2011-02-10 16:00:00, 2011-03-03 16:00:00, 2011-06-03 16:00:00,
2011-05-03 16:00:00, 2011-06-10 16:00:00, 2011-08-01 16:00:00,
2011-12-20 16:00:00], dtype=object)
(Pdb) df2.merge(df,left_index=True,right_on='date')
AAPL GOOG IBM XOM date
1 0 0 4000 0 2011-01-13 16:00:00
2 0 1000 4000 0 2011-01-26 16:00:00
3 0 1000 4000 0 2011-02-02 16:00:00
4 0 1000 4000 4000 2011-02-10 16:00:00
6 0 0 1800 4000 2011-03-03 16:00:00
8 0 0 0 4000 2011-05-03 16:00:00
7 0 0 3300 4000 2011-06-03 16:00:00
9 1200 0 0 4000 2011-06-10 16:00:00
11 1200 0 0 4000 2011-08-01 16:00:00
12 0 0 0 4000 2011-12-20 16:00:00
我尝试了多种方法来获取日期时间索引：
1.) 使用带有日期时间值列表的 reindex() 方法。这会创建一个日期时间索引，但随后会为 DataFrame 中的数据填充 NaN。我猜这是因为原始值与整数索引相关联，并且重新索引到 datetime 试图用默认值填充新索引（如果没有指示填充方法，则为 NaN）。因此：
(Pdb) df.reindex(index=df['date'])
AAPL GOOG IBM XOM date
date
2011-01-13 16:00:00 NaN NaN NaN NaN NaN
2011-01-26 16:00:00 NaN NaN NaN NaN NaN
2011-02-02 16:00:00 NaN NaN NaN NaN NaN
2011-02-10 16:00:00 NaN NaN NaN NaN NaN
2011-03-03 16:00:00 NaN NaN NaN NaN NaN
2011-06-03 16:00:00 NaN NaN NaN NaN NaN
2011-05-03 16:00:00 NaN NaN NaN NaN NaN
2011-06-10 16:00:00 NaN NaN NaN NaN NaN
2011-08-01 16:00:00 NaN NaN NaN NaN NaN
2011-12-20 16:00:00 NaN NaN NaN NaN NaN
2.) 将 DataFrame.merge 与我的原始 df 和第二个数据帧 df2 一起使用，这基本上只是一个日期时间索引，没有别的。所以我最终做了类似的事情：
(pdb) df2.merge(df,left_index=True,right_on='date')
AAPL GOOG IBM XOM date
1 0 0 4000 0 2011-01-13 16:00:00
2 0 1000 4000 0 2011-01-26 16:00:00
3 0 1000 4000 0 2011-02-02 16:00:00
4 0 1000 4000 4000 2011-02-10 16:00:00
6 0 0 1800 4000 2011-03-03 16:00:00
8 0 0 0 4000 2011-05-03 16:00:00
7 0 0 3300 4000 2011-06-03 16:00:00
9 1200 0 0 4000 2011-06-10 16:00:00
11 1200 0 0 4000 2011-08-01 16:00:00
（反之亦然）。但我总是以整数索引结束这种事情。
3.) 从一个带有日期时间索引（从 df 的“日期”字段创建）和一堆空列的空 DataFrame 开始。然后我尝试通过将具有相同名称的列设置为等于 df 中的列来分配每一列：
(Pdb) df2['GOOG']=0
(Pdb) df2
GOOG
date
2011-01-13 16:00:00 0
2011-01-26 16:00:00 0
2011-02-02 16:00:00 0
2011-02-10 16:00:00 0
2011-03-03 16:00:00 0
2011-06-03 16:00:00 0
2011-05-03 16:00:00 0
2011-06-10 16:00:00 0
2011-08-01 16:00:00 0
2011-12-20 16:00:00 0
(Pdb) df2['GOOG'] = df['GOOG']
(Pdb) df2
GOOG
date
2011-01-13 16:00:00 NaN
2011-01-26 16:00:00 NaN
2011-02-02 16:00:00 NaN
2011-02-10 16:00:00 NaN
2011-03-03 16:00:00 NaN
2011-06-03 16:00:00 NaN
2011-05-03 16:00:00 NaN
2011-06-10 16:00:00 NaN
2011-08-01 16:00:00 NaN
2011-12-20 16:00:00 NaN
那么，如何在 pandas 0.7.3 中使用日期时间索引而不是整数索引重新创建 df？我错过了什么？