How to add column from another DataFrame in Pandas?

In Pandas, you can add a column from one DataFrame to another using several methods. The most common approaches are using insert(), direct assignment, or assign().

Using insert() Method

The insert() method allows you to add a column at a specific position in the DataFrame.

Syntax

DataFrame.insert(loc, column, value)

Parameters:

• loc − Position where to insert the column
• column − Name of the new column
• value − Values for the new column

Example

Let's create two DataFrames and add a column from one to another ?

import pandas as pd

# Create first DataFrame
dataFrame1 = pd.DataFrame({
    "Car": ["Audi", "Lamborghini", "BMW", "Lexus"],
    "Place": ["US", "UK", "India", "Australia"],
    "Units": [200, 500, 800, 1000]
})

print("DataFrame 1:")
print(dataFrame1)

# Create second DataFrame
dataFrame2 = pd.DataFrame({
    "Model": [2018, 2019, 2020, 2021], 
    "CC": [3000, 2800, 3500, 3300]
})

print("\nDataFrame 2:")
print(dataFrame2)

# Add Car column from DataFrame1 to DataFrame2
fetched_col = dataFrame1["Car"]
dataFrame2.insert(1, "LuxuryCar", fetched_col)

print("\nDataFrame 2 (Updated):")
print(dataFrame2)

DataFrame 1:
          Car       Place  Units
0        Audi          US    200
1  Lamborghini          UK    500
2         BMW       India    800
3       Lexus   Australia   1000

DataFrame 2:
     CC  Model
0  3000   2018
1  2800   2019
2  3500   2020
3  3300   2021

DataFrame 2 (Updated):
     CC  LuxuryCar  Model
0  3000       Audi   2018
1  2800  Lamborghini   2019
2  3500        BMW   2020
3  3300      Lexus   2021

Using Direct Assignment

You can also add a column using direct assignment, which appends the column at the end ?

import pandas as pd

# Create DataFrames
df1 = pd.DataFrame({"Name": ["Alice", "Bob", "Charlie"], "Age": [25, 30, 35]})
df2 = pd.DataFrame({"Salary": [50000, 60000, 70000]})

print("Original df2:")
print(df2)

# Add Name column from df1 to df2
df2["Name"] = df1["Name"]

print("\nUpdated df2:")
print(df2)

Original df2:
   Salary
0   50000
1   60000
2   70000

Updated df2:
   Salary     Name
0   50000    Alice
1   60000      Bob
2   70000  Charlie

Comparison

Conclusion

Use insert() when you need to place the column at a specific position. Use direct assignment for simple column addition at the end. Both methods require DataFrames to have the same number of rows.