How to select all but the 3 last columns of a dataframe in Python

Use this df.columns being sliced, and putted into a df[...] bracket:

print(df[df.columns[:-3]])

Select everything EXCEPT the last 3 columns, do this using iloc:

In [1639]: df
Out[1639]: 
   a  b  c  d  e
0  1  3  2  2  2
1  2  4  1  1  1

In [1640]: df.iloc[:,:-3]
Out[1640]: 
   a  b
0  1  3
1  2  4