Human: Calcuate mean for selected rows for selected columns in pandas data frame Assistant: 
Here is some code to get mean of columns `2, 5, 6, 7, 8` for all rows in dataframe `df`

df.iloc[:, ([2, 5, 6, 7, 8])].mean(axis=1)

#Warning: this code generation is experimental. Please inspect the code for any bugs before executing.