How To Concatenate Two or More Pandas DataFrames?

Let’s understand how we can concatenate two or more Data Frames. A concatenation of two or more data frames can be done using pandas.concat() method. concat() in pandas works by combining Data Frames across rows or columns. We can concat two or more data frames either along rows  (axis=0) or along columns (axis=1)

Creating Dataframe to Concatenate Two or More Pandas DataFrames

Create two Data Frames which we will be concatenating now. For creating Data frames we will be using numpy and pandas.

Python3

import pandas as pd
import numpy as np

df1 = pd.DataFrame(np.random.randint(25, size=(4, 4)),
                   index=["1", "2", "3", "4"],
                   columns=["A", "B", "C", "D"])

df2 = pd.DataFrame(np.random.randint(25, size=(6, 4)),
                   index=["5", "6", "7", "8", "9", "10"],
                   columns=["A", "B", "C", "D"])

df3 = pd.DataFrame(np.random.randint(25, size=(4, 4)),
                   columns=["A", "B", "C", "D"])

df4 = pd.DataFrame(np.random.randint(25, size=(4, 4)),
                   columns=["E", "F", "G", "H"])

display(df1, df2, df3, df4)

Output:

DataFrame with some random data for testing

Concatenate Two or More Pandas DataFrames

We’ll pass two dataframes to pd.concat() method in the form of a list and mention in which axis you want to concat, i.e. axis=0 to concat along rows, axis=1 to concat along columns.

Python3

# concatenating df1 and df2 along rows
vertical_concat = pd.concat([df1, df2], axis=0)

# concatenating df3 and df4 along columns
horizontal_concat = pd.concat([df3, df4], axis=1)

display(vertical_concat, horizontal_concat)

Output:

Output DataFrame for different axis parameter values