在Pandas Vlookup - 加入还是合并？

Question

I am trying to replicate a Vlookup Excel function using pandas. I have used Join and Merge and both methods give me wrong results.

Df1 has 15 columns with integers and text values and Df2 has 6 columns with mostly text.

I am trying to bring User details from Df2 into Df1 using the column label 'Created By'.

Df1 looks like this:

 CA#   CreatedBy  $
9xxx12  User 1      10
9xxx13  User 2      20
9xxx14  User 3      25

Df2 looks like this:

CreatedBy     Role
User 1         Sales
User 2         Maintenance
User 3         Operations

My expected results would be: DfMerged

CA#     CreatedBy  $   User Role
9xxx12  User 1      10  Sales
9xxx13  User 2      20  Maintenance
9xxx14  User 3      25  Operations

I tried the following code variations, but they don't match all user IDs leaving some blanks in Df1 when there is data in Df2 that matches.

   merged= data_fr1.merge(data_fr2, on=['Created By'], how='left')

   merged2= pd.merge(data_fr1, data_fr2, left_on='Created By', 
   right_on='Created By', how='left')

Someone pointed to this post for an answer: Pandas Merging 101

But I'm still not getting the right results. The 'CreatedBy' field is not populating for all users in Df1. This field is a mix of text and numbers, eg: User1, User2, etc. I wonder if the datatype is interfering with the results.

Answer 1

Does this not get you what you want doing merge? I'm unsure why you have the null column for role and everything under user but you can rename columns.

print('df')
print(df)
print('df2')
print(df2)
print('out_df')
print(out_df)

df.merge(df2[['By', 'Role']], on='By')
df
      CA# Created  By   $
0  9xxx12    User   1  10
1  9xxx13    User   2  20
2  9xxx14    User   3  25
df2
  Created  By         Role
0    User   1        Sales
1    User   2  Maintenance
2    User   3   Operations
out_df
      CA# Created  By   $         User  Role
0  9xxx12    User   1  10        Sales   NaN
1  9xxx13    User   2  20  Maintenance   NaN
2  9xxx14    User   3  25   Operations   NaN
Out[40]: 
      CA# Created  By   $         Role
0  9xxx12    User   1  10        Sales
1  9xxx13    User   2  20  Maintenance
2  9xxx14    User   3  25   Operations

Edit: Sorry, some of the issue is the clipboard parsing. The logic applies. If you're still having issues can you provide examples of "lines" that are not joining properly?