Python - Pandas - Dataframe 如何在使用.count时将notnull添加到列

Question

I am creating a new column that will count all ids but exclude a few rows of customers where the customer's ID has a certain prefix and has no repeat orders

df['newcolumn'] = df[(df.notnull['Date']) & (df['ID'].str.contains('prefix')) & (df['Repeat order'] == 'No')].groupby(['ID'], as_index=False).count()

I am getting below error

TypeError: 'method' object is not subscriptable

Still no difference when I replaced [] with () to resolve above error

Answer 1

change

df.notnull['Date']

to

df['Date'].notnull()