python Dataframe判断单元格为空的方法

import pandas as pd
import numpy as np

df0 = pd.read_excel('')
if df0.iloc[0, 4] is np.nan:  # 判断为空
    print(True)
df0 = df0.fillna('-')  # 填充空单元格
if df0.iloc[0, 4] is np.nan:
    print(True)
df_new = df0[df0['col_name'].apply(lambda x: x is np.nan)] 
print(df_new)