Python quandl 提取日期列表

Question

希望从我的 Quandl 对象中获取日期列表，但我不确定我犯了什么错误。我确信这非常简单，但我似乎无法解决它。

        # -*- coding: utf-8 -*-
        """
        Created on Sat Jun 14 22:54:55 2014

        @author:
        """

        import Quandl;
        import pandas as pd;

        key_="myKey123";

        mydata = Quandl.get("BCHARTS/BITSTAMPUSD", authtoken=key_);

请求有效，我看到:

        >>> mydata.head()
                    Open  High   Low  Close  Volume (BTC)  Volume (Currency)  \
        Date                                                                   
        2011-09-13  5.80  6.00  5.65   5.97     58.371382         346.097389   
        2011-09-14  5.58  5.72  5.52   5.53     61.145984         341.854813   
        2011-09-15  5.12  5.24  5.00   5.13     80.140795         408.259002   
        2011-09-16  4.82  4.87  4.80   4.85     39.914007         193.763147   
        2011-09-17  4.87  4.87  4.87   4.87      0.300000           1.461000   

                    Weighted Price  
        Date                        
        2011-09-13        5.929231  
        2011-09-14        5.590798  
        2011-09-15        5.094272  
        2011-09-16        4.854515  
        2011-09-17        4.870000  

        [5 rows x 7 columns]

我试图通过执行以下操作来获取日期列表:

 >>> mydata["Date"]

给我以下错误:

            self._check_have(item)
          File "/Library/Python/2.7/site-packages/pandas-0.13.0-py2.7-macosx-10.9-intel.egg/pandas/core/internals.py", line 3072, in _check_have
            raise KeyError('no item named %s' % com.pprint_thing(item))
        KeyError: u'no item named Date'

如何仅提取日期？

谢谢

Answer 1

Date 是 DataFrame 上的索引 - 您可以使用 mydata.index 访问它。如果您想让“Date”成为一列，您可以重置索引，如下所示:

In [35]: mydata = mydata.reset_index()

In [36]: mydata['Date']
Out[36]: 
0    2011-09-13
1    2011-09-14
2    2011-09-15
3    2011-09-16
4    2011-09-17
Name: Date, dtype: datetime64[ns]