Python Pandas - How to append rows to a DataFrame

To append rows to a DataFrame, use the concat() method (recommended) or the deprecated append() method. Here, we will create two DataFrames and append one after the other.

Using concat() Method (Recommended)

The concat() method is the modern approach for appending DataFrames ?

import pandas as pd

# Create DataFrame1
dataFrame1 = pd.DataFrame({
    "Car": ['BMW', 'Lexus', 'Audi', 'Jaguar']
})

print("DataFrame1 ...\n", dataFrame1)
print("DataFrame1 length =", len(dataFrame1))

# Create DataFrame2
dataFrame2 = pd.DataFrame({
    "Car": ['Mercedes', 'Tesla', 'Bentley', 'Mustang']
})

print("\nDataFrame2 ...\n", dataFrame2)
print("DataFrame2 length =", len(dataFrame2))

# Append DataFrames using concat()
result = pd.concat([dataFrame1, dataFrame2], ignore_index=True)
print("\nAppending dataframes...\n", result)

DataFrame1 ...
       Car
0      BMW
1    Lexus
2     Audi
3   Jaguar
DataFrame1 length = 4

DataFrame2 ...
        Car
0  Mercedes
1     Tesla
2   Bentley
3   Mustang
DataFrame2 length = 4

Appending dataframes...
        Car
0       BMW
1     Lexus
2      Audi
3    Jaguar
4  Mercedes
5     Tesla
6   Bentley
7   Mustang

Using append() Method (Deprecated)

The append() method is deprecated since pandas 1.4.0 but still works ?

import pandas as pd

# Create DataFrames
dataFrame1 = pd.DataFrame({
    "Car": ['BMW', 'Lexus', 'Audi', 'Jaguar']
})

dataFrame2 = pd.DataFrame({
    "Car": ['Mercedes', 'Tesla', 'Bentley', 'Mustang']
})

# Append using deprecated method
result = dataFrame1.append(dataFrame2, ignore_index=True)
print("Using append()...\n", result)

Using append()...
        Car
0       BMW
1     Lexus
2      Audi
3    Jaguar
4  Mercedes
5     Tesla
6   Bentley
7   Mustang

Key Parameters

When using concat(), important parameters include ?

• ignore_index=True: Resets the index after concatenation
• axis=0: Appends rows (default behavior)
• sort=False: Preserves column order

Comparison

Conclusion

Use pd.concat() for appending DataFrames as it's the recommended modern approach. The append() method is deprecated and should be avoided in new code.