如何判断DataFrame中是否有缺失值？

import pandas as pdimport numpy as npdf = pd.DataFrame(np.random.randn(10,6))# Make a few areas have NaN valuesdf.iloc[1:3,1] = np.nandf.iloc[5,3] = np.nandf.iloc[7:9,5] = np.nan

df.isnull().any() 用来判断某列是否有缺失值
df.isnull().all() 用来判断某列是否全部为空值