Question

我试图通过匹配LineNumbers并写入df1中相应的GeneralDescription的列单元格来使用df4的LineNum列在df1中标识GeneralDescription。我正在寻找一种可扩展的解决方案，以处理具有数千行和其他几行无关紧要的数据帧。如果不是绝对必要的话，我宁愿不合并。我只想写df1的TrueDepartment列，并保持2个数据帧的原始结构不变。谢谢–

df1
    LineNum Warehouse           GeneralDescription
0   2       Empty               Empty
1   3       Empty               Empty
2   4       PBS                 Empty
3   5       Empty               Empty
4   6       Empty               Empty
5   7       General Liability   Empty
6   8       Empty               Empty
7   9       Empty               Empty    

df4
    LineNum GeneralDescription
0   4       TRUCKING
1   6       TRUCKING-GREENVILLE,TN
2   7       Human Resources 

Desired result

    LineNum Warehouse           GeneralDescription
0   2       Empty               Empty
1   3       Empty               Empty
2   4       PBS                 TRUCKING
3   5       Empty               Empty
4   6       Empty               TRUCKING-GREENVILLE,TN
5   7       General Liability   Human Resources
6   8       Empty               Empty
7   9       Empty               Empty

这是我到目前为止对软件包可能有用的代码。因为是我遇到了提示KeyError的错误：“标签[LineNum]不在[index]中”

import pandas as pd
import openpyxl
import numpy as np

data= [[2,'Empty','Empty'],[3,'Empty','Empty'],[4,'PBS','Empty'],[5,'Empty','Empty'],[6,'Empty','Empty'],[7,'General Liability','Empty'],[8,'Empty','Empty'],[9,'Empty','Empty']]
df1=pd.DataFrame(data,columns=['LineNum','Warehouse','GeneralDescription'])

data4 = [[4,'TRUCKING'],[6,'TRUCKING-GREENVILLE,TN'],[7,'Human Resources']]
df4=pd.DataFrame(data4,columns=['LineNum','GeneralDescription'])


for i in range(len(df1.index)):
    if df1.loc[i,'LineNum']==df4.loc['LineNum']:
        df1.loc[i,'GeneralDescription']=df4.loc['GeneralDescription']

Answer 1

将map与Series和fillna通过原始列值创建的df4一起使用：

s = df4.set_index('LineNum')['TrueDepartment']
df1['TrueDepartment'] = df1['LineNum'].map(s).fillna(df1['TrueDepartment'])
print (df1)
   LineNum         Department          TrueDepartment
0        2              Empty                   Empty
1        3              Empty                   Empty
2        4                GBS                TRUCKING
3        5              Empty                   Empty
4        6              Empty  TRUCKING-GREENVILLE,TN
5        7  General Liability         Human Resources
6        8              Empty                   Empty
7        9              Empty                   Empty

使用DataFrame.merge的解决方案：

df = df1.merge(df4,how='left', on='LineNum', suffixes=('','_'))
df['TrueDepartment'] = df['TrueDepartment_'].combine_first(df['TrueDepartment'])
df = df.drop('TrueDepartment_', axis=1)
print (df)
   LineNum         Department          TrueDepartment
0        2              Empty                   Empty
1        3              Empty                   Empty
2        4                GBS                TRUCKING
3        5              Empty                   Empty
4        6              Empty  TRUCKING-GREENVILLE,TN
5        7  General Liability         Human Resources
6        8              Empty                   Empty
7        9              Empty                   Empty

Pandas Python如何使用一个数据帧中的公共数据写入另一个数据帧？

1 个答案: