叢集抽樣

Python 中的抽樣

James Chapman

Curriculum Manager, DataCamp

分層抽樣 vs. 叢集抽樣

分層抽樣

將母體分成子群
在每個子群做簡單隨機抽樣

叢集抽樣

用簡單隨機抽樣挑出部分子群
僅在這些子群中做簡單隨機抽樣

咖啡品種

排列成列與欄的咖啡豆。

varieties_pop = list(coffee_ratings['variety'].unique())

[None, 'Other', 'Bourbon', 'Catimor', 
'Ethiopian Yirgacheffe','Caturra', 
'SL14', 'Sumatra', 'SL34', 'Hawaiian Kona',
'Yellow Bourbon', 'SL28', 'Gesha', 'Catuai',
'Pacamara', 'Typica', 'Sumatra Lintong',
'Mundo Novo', 'Java', 'Peaberry', 'Pacas',
'Mandheling', 'Ruiru 11', 'Arusha',
'Ethiopian Heirlooms', 'Moka Peaberry',
'Sulawesi', 'Blue Mountain', 'Marigojipe', 
'Pache Comun']

第 1 階段：抽樣子群

排列成列與欄的咖啡豆，除三顆外其餘皆為灰色。

import random
varieties_samp = random.sample(varieties_pop, k=3)

['Hawaiian Kona', 'Bourbon', 'SL28']

第 2 階段：各群抽樣

variety_condition = coffee_ratings['variety'].isin(varieties_samp)
coffee_ratings_cluster = coffee_ratings[variety_condition]

coffee_ratings_cluster['variety'] = coffee_ratings_cluster['variety'].cat.remove_unused_categories()

coffee_ratings_cluster.groupby("variety")\
    .sample(n=5, random_state=2021)

第 2 階段輸出

                    total_cup_points        variety       country_of_origin  ...
variety                                                                       
Bourbon       575              82.83        Bourbon               Guatemala   
              560              82.83        Bourbon               Guatemala   
              524              83.00        Bourbon               Guatemala   
              1140             79.83        Bourbon               Guatemala   
              318              83.67        Bourbon                  Brazil   
Hawaiian Kona 1291             73.67  Hawaiian Kona  United States (Hawaii)   
              1266             76.25  Hawaiian Kona  United States (Hawaii)   
              488              83.08  Hawaiian Kona  United States (Hawaii)   
              461              83.17  Hawaiian Kona  United States (Hawaii)   
              117              84.83  Hawaiian Kona  United States (Hawaii)   
SL28          137              84.67           SL28                   Kenya   
              452              83.17           SL28                   Kenya   
              224              84.17           SL28                   Kenya   
              66               85.50           SL28                   Kenya   
              559              82.83           SL28                   Kenya

多階段抽樣

叢集抽樣是一種多階段抽樣
可有超過 2 個階段
例如，全國性調查可依序抽樣州、縣、市與鄰里

一起來練習吧！

Python 中的抽樣