Pandas - 如何使用另一个 dataframe 从 dataframe 中提取列？

Question

I am looking to extract columns from a dataframe using another dataframe. I don't want to hard code the column headers into the code as the data comes from a csv and columns can be added with different headers. Tried with.loc and using iterations, but nothing seems to work. This is what I have for code which are all from two different csv documents...

df1 =

    Date     a   b   c  d
 11/11/2011  2   3   4  5
 11/12/2011  3   4   5  6
 11/13/2011  4   5   6  7         

df1 was translated using a.pivot and a,b,c,d's column header is Symbol and

df2=

Symbol
    b
    d

The expect outcome is...

     b   d
 x   3   5
 y   4   6
 z   5   7  

Tried doing

df1.loc(df2)

but got a 'DataFrame' objects are mutable, thus they cannot be hashed error

Thanks for the help!

Answer 1

You can do this:

In [157]: df1[df2['Symbol']]
Out[157]: 
   b  d
0  3  5
1  4  6
2  5  7