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Python Pandas - Count the number of rows in each group
Use the group.size() to count the number of rows in each group. Import the required library −
import pandas as pd
Create a DataFrame −
dataFrame = pd.DataFrame({'Product Category': ['Computer', 'Mobile Phone', 'Electronics', 'Electronics', 'Computer', 'Mobile Phone'],'Quantity': [10, 50, 10, 20, 25, 50],'Product Name': ['Keyboard', 'Charger', 'SmartTV', 'Camera', 'Graphic Card', 'Earphone'] })
Group by columns −
dataFrame.groupby(["Product Category", "Quantity"])
Now, count the group size to get the count of rows in each group.
Example
Following is the complete code −
import pandas as pd # create a dataframe dataFrame = pd.DataFrame({'Product Category': ['Computer', 'Mobile Phone', 'Electronics', 'Electronics', 'Computer', 'Mobile Phone'],'Quantity': [10, 50, 10, 20, 25, 50],'Product Name': ['Keyboard', 'Charger', 'SmartTV', 'Camera', 'Graphic Card', 'Earphone'] }) # dataframe print"Dataframe...\n",dataFrame # grouping columns new_group = dataFrame.groupby(["Product Category", "Quantity"]) # group size new_group = new_group.size() # dataframe print"\nUpdated Dataframe...\n",new_group
Output
This will produce the following output −
Dataframe... Product Category Product Name Quantity 0 Computer Keyboard 10 1 Mobile Phone Charger 50 2 Electronics SmartTV 10 3 Electronics Camera 20 4 Computer Graphic Card 25 5 Mobile Phone Earphone 50 Updated Dataframe... Product Category Quantity Computer 10 1 25 1 Electronics 10 1 20 1 Mobile Phone 50 2 dtype: int64
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