Python Pandas – Đếm quan sát (observations)

Để đếm quan sát, dùng groupby() rồi count() trên kết quả.

Nhập thư viện:

import pandas as pd

Tạo DataFrame:

dataFrame = pd.DataFrame({
    'Product Name': ['Keyboard', 'Charger', 'SmartTV', 'Camera', 'Graphic Card', 'Earphone'],
    'Product Category': ['Computer', 'Mobile Phone', 'Electronics', 'Electronics', 'Computer', 'Mobile Phone'],
    'Quantity': [10, 50, 10, 20, 25, 50]
})

Nhóm cột trùng lặp:

group = dataFrame.groupby("Product Category")

Lấy count:

group.count()

Ví dụ

import pandas as pd

dataFrame = pd.DataFrame({
    'Product Name': ['Keyboard', 'Charger', 'SmartTV', 'Camera', 'Graphic Card', 'Earphone'],
    'Product Category': ['Computer', 'Mobile Phone', 'Electronics', 'Electronics', 'Computer', 'Mobile Phone'],
    'Quantity': [10, 50, 10, 20, 25, 50]
})
print("Dataframe...\n", dataFrame)

group = dataFrame.groupby("Product Category")
print("\nResultant DataFrame...\n", group.count())

Đầu ra

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

Resultant DataFrame...
                 Product Name  Quantity
Product Category
Computer                   2        2
Electronics                2        2
Mobile Phone               2        2