Python：Pivot 表，按類別計數分組

Question

假設我有一個看起來像這樣的文件：

+---------+---------+-------+
| Product | Quality | Origin|
+---------+---------+-------+
| Apple   | Good    |       |
+---------+---------+-------+
| Apple   | Bad     |       |
+---------+---------+-------+
| Apple   | Bad     |       |
+---------+---------+-------+
| Orange  | Good    |       |
+---------+---------+-------+
| .       |         |       |
+---------+---------+-------+
| .       |         |       |
+---------+---------+-------+
| Grape   | Good    |       |
+---------+---------+-------+

我想用計數制作一個 pivot 結果：

+---------+---------------+------+-----+
| Product | Total Number  | Good | Bad |
+---------+---------------+------+-----+
| Apple   | 5             | 3    | 2   |
+---------+---------------+------+-----+
| Orange  | 8             | 5    | 3   |
+---------+---------------+------+-----+
| Grape   | 3             | 1    | 2   |
+---------+---------------+------+-----+
| Total   | 16            | 9    | 7   |
+---------+---------------+------+-----+

我正在使用groupby和count來獲取總數：

Total_Product = ProdcutFile.groupby('Product').count()

但是我怎樣才能使結果表包含好和壞的計數？

Answer 1

這是一種方法，使用分配和 pivot 表。 assign 語句生成一列，並將其相加提供最終表中的計數。

from io import StringIO
import pandas as pd

data = '''Product  Quality 
Apple    Good    
Apple    Bad     
Apple    Bad     
Orange   Good
Orange   Bad
Grape    Good    
'''

df = (pd.read_csv(StringIO(data), sep='\s+', engine='python')
        .assign(counter = 1)
        .pivot_table(index='Product', 
                     columns='Quality', 
                     values='counter', 
                     aggfunc=sum, 
                     fill_value=0, 
                     margins=True, 
                     margins_name='Totals')
     )
print(df)

Quality  Bad  Good  Totals
Product                   
Apple      2     1       3
Grape      0     1       1
Orange     1     1       2
Totals     3     3       6

（提供列名稱和排序很簡單，未顯示。）