Concatenate several DataFrames (sorted with the index, add new columns)

pd.concat([df list], axis=1) makes a new DataFrames in which each column is sorted with the index

>>> df1 = pd.DataFrame([[1],[2]],columns=['number'],index=['f1','f2'])

>>> df1

   number

f1       1

f2       2

>>> df2 = pd.DataFrame([['b'],['a']],columns=['letter'],index=['f2','f1'])

>>> df2

  letter

f2      b

f1      a

>>> pd.concat([df1,df2],axis=1)

   number letter

f1       1      a

f2       2      b

*Note the order of rows was automatically sorted to match the index.

If axis=0, df2 will be added as new rows.