Selecting last n columns and excluding last n columns in dataframe

Question

How do I:

1. Select last 3 columns in a dataframe and create a new dataframe?

I tried:

y = dataframe.iloc[:,-3:]

Answer 1

The most efficient way:

1. Select last n columns

df1 = df.iloc[:,-n:]

2. Exclude last n columns

df1 = df.iloc[:,:-n]