python教程：Pandas之Fillna填充缺失数据的方法

不念不忘少年蓝@ 2023-07-09 12:24 7阅读 0赞

Pandas之Fillna填充缺失数据的方法  
约定：

import pandas as pd
    import numpy as np
    from numpy import nan as NaN

填充缺失数据  
fillna()是最主要的处理方式了。

df1=pd.DataFrame([[1,2,3],[NaN,NaN,2],[NaN,NaN,NaN],[8,8,NaN]])
    df1

代码结果：  
![在这里插入图片描述][20200228205827834.png]  
用常数填充：  
`df1.fillna(100)`  
代码结果：![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70]  
通过字典填充不同的常数：

df1.fillna({ 0:10,1:20,2:30})

代码结果：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 1]  
传入inplace=True直接修改原对象：

df1.fillna(0,inplace=True)
    df1

代码结果：![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 2]  
传入method=” “改变插值方式：

df2=pd.DataFrame(np.random.randint(0,10,(5,5)))
    df2.iloc[1:4,3]=NaN;df2.iloc[2:4,4]=NaN
    df2

代码结果：![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 3]

df2.fillna(method='ffill')#用前面的值来填充

代码结果：![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 4]  
传入limit=” “限制填充个数：`df2.fillna(method='bfill',limit=2)`  
代码结果：![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 5]  
传入axis=” “修改填充方向：

df2.fillna(method="ffill",limit=1,axis=1)

代码结果：![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 6]

推荐我们的python学习基地，[点击进入][Link 1]，看老程序是如何学习的！从基础的python脚本、爬虫、django、数据挖掘等编程技术，工作经验，还有前辈精心为学习python的小伙伴整理零基础到项目实战的资料，！每天都有程序员定时讲解Python技术，分享一些学习的方法和需要留意的小细节

[20200228205827834.png]: https://img-blog.csdnimg.cn/20200228205827834.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200228205857903.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/2020022821000636.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20200228210026633.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 3]: https://img-blog.csdnimg.cn/20200228210118512.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 4]: https://img-blog.csdnimg.cn/20200228210137703.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 5]: https://img-blog.csdnimg.cn/20200228210200108.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1_size_16_color_FFFFFF_t_70 6]: https://img-blog.csdnimg.cn/20200228210223980.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2hhb3h1bjA1,size_16,color_FFFFFF,t_70
[Link 1]: https://jq.qq.com/?_wv=1027&k=5ipV5It