To groupby columns and count the occurrences of each combination in Pandas, we use the DataFrame.groupby() with size(). The groupby() method separates the DataFrame into groups.
At first, let us import the pandas library with an alias pd −
import pandas as pd
Initialize the data of lists −
# initializing the data
mylist = {'Car': ['BMW', 'Mercedes', 'Lamborgini', 'Audi', 'Mercedes', 'Porche', 'RollsRoyce', 'BMW'], 'Place': ['Delhi', 'Hyderabad', 'Chandigarh', 'Bangalore', 'Hyderabad', 'Mumbai', 'Mumbai','Delhi'],
'Sold': [95, 80, 80, 75, 90, 90, 95, 50 ]}Next, we will create a DataFrame −
# DataFrame dataFrame = pd.DataFrame(mylist, columns=['Car', 'Place', 'Sold'])
Now, use the groupby() to count the occurrence with the size() −
print("Counting the occurrences...")
res = dataFrame.groupby(['Car', 'Place']).size()Following is the code to count the occurrences of each combination −
Example
# importing library
import pandas as pd
# initializing the data
mylist = {'Car': ['BMW', 'Mercedes', 'Lamborgini', 'Audi', 'Mercedes', 'Porsche', 'RollsRoyce', 'BMW'],
'Place': ['Delhi', 'Hyderabad', 'Chandigarh', 'Bangalore', 'Hyderabad', 'Mumbai', 'Mumbai','Delhi'],
'Sold': [95, 80, 80, 75, 90, 90, 95, 50 ]}
# DataFrame
dataFrame = pd.DataFrame(mylist, columns=['Car', 'Place', 'Sold'])
print(dataFrame)
print("Counting the occurrences...")
res = dataFrame.groupby(['Car', 'Place']).size()
# Displaying the occurrences
print(res)Output
This will produce the following output −
Car Place Sold 0 BMW Delhi 95 1 Mercedes Hyderabad 80 2 Lamborgini Chandigarh 80 3 Audi Bangalore 75 4 Mercedes Hyderabad 90 5 Porsche Mumbai 90 6 RollsRoyce Mumbai 95 7 BMW Delhi 50 Counting the occurrences... Car Place Audi Bangalore 1 BMW Delhi 2 Lamborgini Chandigarh 1 Mercedes Hyderabad 2 Porsche Mumbai 1 RollsRoyce Mumbai 1 dtype: int64