Make column from pandas dataframe index

问题

I have a dataframe where I would like to turn the data in the (first level of the) index into a column. Practically my df looks like this:

         col1
CoI     
 AK   0     1
      1    31
      2   NaN 
 BB   0     5
      1    31
      2   NaN 

And I would like to turn it into this:

      col1  CoI

   0     1   AK
   1    31   AK
   2   NaN   AK
   0     5   BB
   1    31   BB
   2   NaN   BB

How can I best do this? I think this is a rather basic functionality, but as with many other "basic" pandas things I cannot find info on this anywhere.

Many Thanks,

回答1:

df.reset_index(level=0, inplace=True) should do it. See the docs here.

来源：https://stackoverflow.com/questions/20228998/make-column-from-pandas-dataframe-index