Empty Result When Merging DataFrames

Question

I would like to merge patient_df:

id    first_name      last_name      birthdate
1           John            Doe     2001-12-21
2          David          Xavier    1999-11-24

With this contact_df (based on columns {birthdate,first_name,last_name}):

first_name      last_name      birthdate      city      Postal   
     David          Xavier    1999-11-24   Buffalo      P9B3R3
      John            Doe     2001-12-21    Irvine      V4A3E2

Types of columns are all object, except id is int64

It returns empty when I tried this

df_merged = pd.merge(patient_df, contact_df, how='inner', on=['birthdate','first_name','last_name'])

The result is:

Empty DataFrame
Column: [id, first_name, last_name, birthdate, city, postal]
Index: []

Could you please help me?

Welcome to SO. Please don't post images. Take a tour of [how-to-make-good-reproducible-pandas-examples](https://stackoverflow.com/questions/20109391/how-to-make-good-reproducible-pandas-examples). — Shubham Sharma, Jun 14 '20 at 09:58
I guess your keys are not matching between two dataframes, check for any whitespace in names. — Shubham Sharma, Jun 14 '20 at 15:31

score 1 · Accepted Answer · answered Jun 14 '20 at 10:54

1

To use merge correctly, you should try this line of code:

patient_df.merge(contact_df, how='inner', on=['birthdate','first_name','last_name'])

Hope it works correctly now!

Cheers, T

answered Jun 14 '20 at 10:54

t.novaes

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Empty Result When Merging DataFrames

1 Answers1