How to rearrange Pandas column sequence?

Question

>>> df =DataFrame({\'a\':[1,2,3,4],\'b\':[2,4,6,8]})
>>> df[\'x\']=df.a + df.b
>>> df[\'y\']=df.a - df.b
>>> df
   a  b   x  y
0          


        

Answer 1

Feel free to disregard this solution as subtracting a list from an Index does not preserve the order of the original Index, if that's important.

In [61]: df.reindex(columns=pd.Index(['x', 'y']).append(df.columns - ['x', 'y']))
Out[61]: 
    x  y  a  b
0   3 -1  1  2
1   6 -2  2  4
2   9 -3  3  6
3  12 -4  4  8