如何通过Pandas.DataFrame中的值筛选出值

Question

The dataFrame that I want to filter is:

         High    Low  Close    Volume
Date                                     
2014-06-02  634.8  622.5  628.6  13149746
2014-06-03  638.7  628.2  637.5  10419625
2014-06-04  647.9  636.1  644.8  11949821
2014-06-05  649.4  642.6  647.4  10657616
2014-06-06  651.3  644.5  645.6  12497800 
2014-06-09   93.9   91.8   93.7  74876982
2014-06-10   95.0   93.6   94.2  62458587
2015-06-11   94.8   93.5   93.9  45484122

I would like to select, for example from 2014-06-05 to the current date(2015-06-11). What's is the most proper way to select by comparing strings in the Date column?

Answer 1

I'd convert the 'Date' column to dtype datetime so you can do date string comparison and then you can do the following:

In [26]:

df[(df['Date'] > '2014-06-05') & (df['Date'] < '2015-06-11')]
Out[26]:
        Date   High    Low  Close    Volume
4 2014-06-06  651.3  644.5  645.6  12497800
5 2014-06-09   93.9   91.8   93.7  74876982
6 2014-06-10   95.0   93.6   94.2  62458587

So first the conversion:

df['Date'] = pd.to_datetime(df['Date'])

Then the boolean condition requires using the & operator for AND and parentheses due to operator precedence.

EDIT

It looks like your 'Date' data is in fact the index, in which case you can still perform the datetime conversion like so: df.index = pd.to_datetime(df.index) and then filter like this:

In [28]:

df[(df.index > '2014-06-05') & (df.index < '2015-06-11')]
Out[28]:
             High    Low  Close    Volume
Date                                     
2014-06-06  651.3  644.5  645.6  12497800
2014-06-09   93.9   91.8   93.7  74876982
2014-06-10   95.0   93.6   94.2  62458587