1 #encoding=utf-8
 2 import numpy as np
 3 import pandas as pd
 4 df = pd.DataFrame(
 5      [
 6          ("bird", "Falconiformes", 389.0),
 7         ("bird", "Psittaciformes", 24.0),
 8          ("mammal", "Carnivora", 80.2),
 9          ("mammal", "Primates", np.nan),
10        ("mammal", "Carnivora
 
", 58),
11      ],
12      index=["falcon", "parrot", "lion", "monkey", "leopard"],
13     columns=("class", "order", "max_speed"),
14    )
15 df.groupby(by=['class','order'])['max_speed'].count().rename('speed').to_frame().reset_index()

第15行 groupby為使用兩個欄位分組，count()取分組後max_speed的出現次數，rename重新命名Series的列，to_frame將Series轉為DataFrame,reset_index重建索引,方便匯出到excel

重建索引前後對比

RangeIndex(start=0, stop=4, step=1)

MultiIndex([(  'bird',  'Falconiformes'),
            (  'bird', 'Psittaciformes'),
            ('mammal',      'Carnivora'),
            ('mammal',       'Primates')],
           names=['class', 'order'])