Python - Merge DataFrames of different length

To merge dataframes of different length, we need to use the merge() method. Let’s say the following is our 1st DataFrame with length 4 −

dataFrame1 = pd.DataFrame(    {       "Car": ['BMW', 'Lexus', 'Audi', 'Jaguar']    } ) print("DataFrame1 ...\n",dataFrame1) print("DataFrame1 length = ", len(dataFrame1))

Following is our 2nd DataFrame with length 6 −

dataFrame2 = pd.DataFrame(    {       "Car": ['BMW', 'Lexus', 'Audi', 'Mercedes', 'Jaguar', 'Bentley']    } ) print("\nDataFrame2 ...\n",dataFrame2) print("DataFrame2 length = ", len(dataFrame2))

Now, merge DataFrames using the merge() −

mergedRes = dataFrame2.merge(dataFrame1, how='left')

Example

Following is the code −

import pandas as pd # Create DataFrame1 dataFrame1 = pd.DataFrame(    {       "Car": ['BMW', 'Lexus', 'Audi', 'Jaguar']    } ) print("DataFrame1 ...\n",dataFrame1) # Find length of DataFrame1 print("DataFrame1 length = ", len(dataFrame1)) # Create DataFrame2 dataFrame2 = pd.DataFrame(    {       "Car": ['BMW', 'Lexus', 'Audi', 'Mercedes', 'Jaguar', 'Bentley'] } ) print("\nDataFrame2 ...\n",dataFrame2) # Find length of DataFrame2 print("DataFrame2 length = ", len(dataFrame2)) # merge DataFrames mergedRes = dataFrame2.merge(dataFrame1, how='left') print("\nMerged data frame...\n", mergedRes)

Output

This will produce the following output −

DataFrame1 ...       Car 0     BMW 1   Lexus 2    Audi 3  Jaguar DataFrame1 length = 4 DataFrame2 ...         Car 0       BMW 1     Lexus 2      Audi 3  Mercedes 4    Jaguar 5   Bentley DataFrame2 length = 6 Merged data frame...         Car 0       BMW 1     Lexus 2      Audi 3  Mercedes 4    Jaguar 5   Bentley