set value on multiple columns conditionally

Question

I have a set of columns that reflect components to another column. When that column is negative, I will need to zero it out. I need to also zero out all of the component columns. How do I do this?

filter_col = [col for col in t18_df if col.startswith('aum_')]
t18_df.loc[t18_df['AUM'] < 0] # these rows should have zeroed values only on filter_col

Answer 1

You can just pass the filter_col into loc :

filter_col = [col for col in t18_df if col.startswith('aum_')]

# zero out filter_col
t18_df.loc[t18_df['AUM'] < 0, filter_col] = 0

# zero out AUM itself
t18_df.loc[t18_df['AUM'] < 0, 'AUM'] = 0
# also
# t18_df['AUM'] = t18_df['AUM'].clip(0)