CODEWITHSUNDEEP
pythonpandas
Ajay jadhav
Ajay jadhav

Reputation: 163

Addition of 2 dataframes column to column by unique column in pandas

I have 2 dataframes 

df1

a b c 
1 2 3
2 4 5
3 6 7

and 

df2
a b c
1 3 4
3 1 8

I want output to be

df3 
a b c
1 5 7
2 4 5
3 7 15

I tried df1.add(df2,axis='c') but not getting exact output.

referring this link http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.add.html

Upvotes: 2

Views: 241

Answers (2)

jezrael
jezrael

Reputation: 863166

You need set_index by column a in both df with add and parameter fill_value=0.

Last if necessary convert values to int and reset_index:

df = df1.set_index('a').add(df2.set_index('a'),fill_value=0).astype(int).reset_index()
print (df)
   a  b   c
0  1  5   7
1  2  4   5
2  3  7  15

For removing not common rows omit fill_value and add dropna if no NaN in both DataFrames

df = df1.set_index('a').add(df2.set_index('a')).dropna().astype(int).reset_index()
print (df)
   a  b   c
0  1  5   7
1  3  7  15

Upvotes: 4

McGrady
McGrady

Reputation: 11477

Maybe you can try this:

>>> import pandas as pd
>>>
>>> df1 = pd.DataFrame([(1, 2, 3), (2, 4, 5), (3, 6, 7)], columns=['a', 'b', 'c'])
>>>
>>> df2 = pd.DataFrame([(1, 3, 4), (3, 1, 8)], columns=['a', 'b', 'c'])
>>>
>>> df1.index = df1['a']
>>> del df1['a']
>>>
>>> df2.index = df2['a']
>>> del df2['a']
>>>
>>> df1.add(df2, fill_value=0)
     b     c
a
1  5.0   7.0
2  4.0   5.0
3  7.0  15.0

Or use set_index() method:

>>> df1.set_index('a').add(df2.set_index('a'), fill_value=0)
     b     c
a
1  5.0   7.0
2  4.0   5.0
3  7.0  15.0

Upvotes: 1

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