用另一个数据框的值填充数据框列

Question

I have two dataframes:

import pandas
import numpy
entry1= pandas.datetime(2014,6,1)
entry2= pandas.datetime(2014,6,2)
df1=pandas.DataFrame(numpy.array([[1,1],[2,2],[3,3]]), columns=['eins','zwei'], index=[entry1, entry1, entry2])   
df2=pandas.DataFrame(numpy.array([[2,3],[3,3]]), columns=['eins','zwei'], index=[entry1, entry2])  

and I want to insert a new column into df1 that looks up the corresponding index values in df2 and inserts the value of column 'eins' that has the same index value as df1 into the new column of df1.The result is supposed to look like this:

df1['new column']=[2,2,3]

How to do this kind of filling?

Answer 1

>>> df1.join(df2['eins'], rsuffix='_new')
            eins  zwei  eins_new
2014-06-01     1     1         2
2014-06-01     2     2         2
2014-06-02     3     3         3