【Python】pandas 删除空值数据 dropna

dropna

import pandas as pd
import numpy as np

df = pd.DataFrame(
    {
        "name": ['Alfred', 'Batman', 'Catwoman'],
        "toy": [np.nan, 'Batmobile', 'Bullwhip'],
        "born": [pd.NaT, pd.Timestamp("1940-04-25"), pd.NaT]
    }
)

print(df)
'''
       name        toy       born
0    Alfred        NaN        NaT
1    Batman  Batmobile 1940-04-25
2  Catwoman   Bullwhip        NaT
'''

df.dropna()  # 默认 axis=0, 判断行
'''
     name        toy       born
1  Batman  Batmobile 1940-04-25
'''
df.dropna(axis=1)  # 判断列
'''
       name
0    Alfred
1    Batman
2  Catwoman
'''
df.dropna(axis=0, how='all')  # 指定所有值全为缺失值才删除
'''
       name        toy       born
0    Alfred        NaN        NaT
1    Batman  Batmobile 1940-04-25
2  Catwoman   Bullwhip        NaT
'''
df.dropna(axis=0, thresh=2)  # 指定至少出现过两个缺失值才删除
'''
       name        toy       born
1    Batman  Batmobile 1940-04-25
2  Catwoman   Bullwhip        NaT
'''
df.dropna(subset=['name', 'born'])  # 指定哪几列中含有缺失值才删除
'''
     name        toy       born
1  Batman  Batmobile 1940-04-25
'''