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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
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