Pandas merge or update an empty dataframe with another dataframe?

Question

I have an empty dataframe df1

import numpy as np
import pandas as pd

df1 = pd.DataFrame(columns=['A','B','C','D','E'])

df1
A   B   C   D   E

I want to merge or update this dataframe with another dataframe df2

df2 = pd.DataFrame({ 'B': [1,2,3],
                     'D': [4,5,6],
                     'E': [7,8,9]})
df2
    B   D   E
0   1   4   7
1   2   5   8
2   3   6   9

to get a merged or updated dataframe as

    A   B   C   D   E
0   NaN 1   NaN 4   7
1   NaN 2   NaN 5   8
2   NaN 3   NaN 6   9

Besides, efficiency is required because I have a long df1 and df2.

Any good idea? Thank you.

At start you are saying you have empty df1 at end you are saying its very long df1. which one is it ? — Surjit Samra
– Surjit Samra, Commented Jan 10, 2023 at 5:45

mozway · Accepted Answer · 2023-01-10 05:51:13Z

3

Use reindex:

df1 = df2.reindex(columns=df1.columns)

Output:

    A  B   C  D  E
0 NaN  1 NaN  4  7
1 NaN  2 NaN  5  8
2 NaN  3 NaN  6  9

answered Jan 10, 2023 at 5:51

mozway

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Comments

Akash Kumar · Accepted Answer · 2023-01-10 05:48:07Z

2

try this

import pandas as pd
pd.concat((df1, df2))

answered Jan 10, 2023 at 5:48

Akash Kumar

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