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Python Pandas - Merge DataFrame with indicator value
To merge Pandas DataFrame, use the merge() function. In that, you can set the parameter indicator to True or False. If you want to check which dataframe has a specific record, then use −
indicator= True
As shown above, using above parameter as True, adds a column to the output DataFrame called “_merge”.
At first, let us import the pandas library with an alias −
import pandas as pd
Let us create DataFrame1 −
dataFrame1 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Audi', 'Mustang', 'Bentley', 'Jaguar'],
"Units": [100, 150, 110, 80, 110, 90]
}
)
Create DataFrame2 −
dataFrame2 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Tesla', 'Mustang', 'Mercedes', 'Jaguar'],
"Reg_Price": [7000, 1500, 5000, 8000, 9000, 6000]
}
)Now, merge DataFrames with indicator value True −
# merge DataFrames with indicator value mergedRes = pd.merge(dataFrame1, dataFrame2, how ="left",indicator=True)
Example
Following is the code −
import pandas as pd
# Create DataFrame1
dataFrame1 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Audi', 'Mustang', 'Bentley', 'Jaguar'],
"Units": [100, 150, 110, 80, 110, 90]
}
)
print"DataFrame1 ...\n",dataFrame1
# Create DataFrame2
dataFrame2 = pd.DataFrame(
{
"Car": ['BMW', 'Lexus', 'Tesla', 'Mustang', 'Mercedes', 'Jaguar'],
"Reg_Price": [7000, 1500, 5000, 8000, 9000, 6000]
}
)
print"\nDataFrame2 ...\n",dataFrame2
# merge DataFrames with indicator value
mergedRes = pd.merge(dataFrame1, dataFrame2, how ="left",indicator=True)
print"\nMerged dataframe...\n", mergedRes
Output
This will produce the following output. Here, “both””in “_merge displays that both the value is in both the DataFrames −
DataFrame1 ... Car Units 0 BMW 100 1 Lexus 150 2 Audi 110 3 Mustang 80 4 Bentley 110 5 Jaguar 90 DataFrame2 ... Car Reg_Price 0 BMW 7000 1 Lexus 1500 2 Tesla 5000 3 Mustang 8000 4 Mercedes 9000 5 Jaguar 6000 Merged dataframe... Car Units Reg_Price _merge 0 BMW 100 7000.0 both 1 Lexus 150 1500.0 both 2 Audi 110 NaN left_only 3 Mustang 80 8000.0 both 4 Bentley 110 NaN left_only 5 Jaguar 90 6000.0 both
Updated on: 15-Sep-2021
4K+ Views
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