Python - How to Concatenate Two or More Pandas DataFrames along rows?

To concatenate two or more Pandas DataFrames along rows, use the pd.concat() method with axis=0. This combines DataFrames vertically, stacking them on top of each other.

Syntax

pd.concat([df1, df2, df3, ...], axis=0)

Creating Sample DataFrames

First, let's create three sample DataFrames to demonstrate concatenation ?

import pandas as pd

# Create DataFrame1
dataFrame1 = pd.DataFrame({
    "Col1": [10, 20, 30],
    "Col2": [40, 50, 60],
    "Col3": [70, 80, 90]
}, index=[0, 1, 2])

print("DataFrame1:")
print(dataFrame1)

DataFrame1:
   Col1  Col2  Col3
0    10    40    70
1    20    50    80
2    30    60    90

import pandas as pd

# Create DataFrame2
dataFrame2 = pd.DataFrame({
    "Col1": [100, 110, 120],
    "Col2": [130, 140, 150],
    "Col3": [160, 170, 180]
}, index=[3, 4, 5])

print("DataFrame2:")
print(dataFrame2)

DataFrame2:
   Col1  Col2  Col3
3   100   130   160
4   110   140   170
5   120   150   180

import pandas as pd

# Create DataFrame3
dataFrame3 = pd.DataFrame({
    "Col1": [200, 210, 220],
    "Col2": [230, 240, 250],
    "Col3": [260, 270, 280]
}, index=[6, 7, 8])

print("DataFrame3:")
print(dataFrame3)

DataFrame3:
   Col1  Col2  Col3
6   200   230   260
7   210   240   270
8   220   250   280

Concatenating DataFrames Along Rows

Now let's concatenate all three DataFrames along rows using axis=0 ?

import pandas as pd

# Create three DataFrames
dataFrame1 = pd.DataFrame({
    "Col1": [10, 20, 30],
    "Col2": [40, 50, 60],
    "Col3": [70, 80, 90]
}, index=[0, 1, 2])

dataFrame2 = pd.DataFrame({
    "Col1": [100, 110, 120],
    "Col2": [130, 140, 150],
    "Col3": [160, 170, 180]
}, index=[3, 4, 5])

dataFrame3 = pd.DataFrame({
    "Col1": [200, 210, 220],
    "Col2": [230, 240, 250],
    "Col3": [260, 270, 280]
}, index=[6, 7, 8])

# Concatenate all DataFrames along rows (axis=0)
result = pd.concat([dataFrame1, dataFrame2, dataFrame3], axis=0)
print("Concatenated DataFrame:")
print(result)

Concatenated DataFrame:
   Col1  Col2  Col3
0    10    40    70
1    20    50    80
2    30    60    90
3   100   130   160
4   110   140   170
5   120   150   180
6   200   230   260
7   210   240   270
8   220   250   280

Key Points

• axis=0 concatenates DataFrames vertically (along rows)
• The original index values are preserved in the result
• All DataFrames must have the same column structure
• Pass a list of DataFrames to concatenate multiple DataFrames at once

Conclusion

Use pd.concat() with axis=0 to stack DataFrames vertically along rows. This method preserves the original indices and efficiently combines multiple DataFrames with matching column structures.