df['cum_sum'] = df['val1'].cumsum()
df['cum_perc'] = 100*df['cum_sum']/df['val1'].sum()
This will add the columns to df. If you want a copy, copy df first and then do these operations on the copy.
df['cum_sum'] = df['val1'].cumsum()
df['cum_perc'] = 100*df['cum_sum']/df['val1'].sum()
This will add the columns to df. If you want a copy, copy df first and then do these operations on the copy.