How to merge two dataframes with pandas Python

Question

here are 2 dataframes :

d1 = pd.DataFrame({'a': [19, 65, 7, 49, 66, 89, 545],
                  'b': [4, 6, 6, 90, 5, 77, 767],
                  'c': [34, 78, 65, 666, '', '', '']})

d2 = pd.DataFrame({'c': [34, 78, 65, '', ''],
                  'd': [4, 6, 6, 90, 767]})

I would like to make a merge between them with "c" column as jointure.

In my case, I use this :

df = pd.merge(d1, d2, how='left')

But the result is not good. In fact, I have some doublons, plus the final result should be a dataframe with the same length of d1. In my case It is not true.

Here is the result I would like to have :

df = pd.DataFrame({'a': [19, 65, 7, 49, 66, 89, 545],
                  'b': [4, 6, 6, 90, 5, 77, 767],
                  'c': [34, 78, 65, 666, '', '', ''],
                  'd': [4, 6, 6, 90, 767, '', '']})

So, how do you want to merge them? There are 5 ways of merging dataframes: pandas.pydata.org/pandas-docs/stable/reference/api/… — ForceBru
– ForceBru, Commented Jun 28, 2021 at 16:10
I want to join the two dataframe on "c" column without duplicate row — ahmedaao
– ahmedaao, Commented Jun 28, 2021 at 16:13

Anurag Dabas · Accepted Answer · 2021-06-28 17:27:44Z

2

IIUC:

use concat() and fillna():

df=pd.concat([d1,d2.pop('d')],axis=1).fillna('')
#OR
df=pd.concat([d1,d2['d']],axis=1).fillna('')

Now If you print df you will get your expected output

edited Jun 28, 2021 at 17:27

answered Jun 28, 2021 at 16:11

Anurag Dabas

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4 Comments

ahmedaao Over a year ago

It is not exactly the result I want. You can see it in the description

Anurag Dabas Over a year ago

@ahmedaao why you are getting 867 at index 4 in your expected output?

ahmedaao Over a year ago

sorry. Mistake It is 767

Anurag Dabas Over a year ago

@ahmedaao Updated answer.....Kindly have a look :)

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