มีอาจารย์จากภาควิชาบัญชีหรือชีววิทยากี่คน?
How many professors who are from either Accounting or Biology department?
df_department = pd.DataFrame(columns=['dept_code', 'dept_name']); df_professor = pd.DataFrame(columns=['dept_code'])
len(df_professor[df_professor['dept_code'].isin(df_department[(df_department['dept_name'] == 'Accounting') | (df_department['dept_name'] == 'Biology')]['dept_code'])])