Pandas GroupBy ō Ā Count the occurrences of each combination

为了在Pandas中按列分组并计算每个组合的出现次数，我们使用DataFrame.groupby()和size()。groupby()方法将DataFrame分成了多组。

首先，让我们使用别名pd导入pandas库 –

import pandas as pd

初始化列表的数据 –

# 初始化数据
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 ]}

接下来，我们将创建一个DataFrame –

# DataFrame
dataFrame = pd.DataFrame(mylist, columns=['Car', 'Place', 'Sold'])

现在，使用groupby()和size()计算每个组合的出现次数 –

print("Counting the occurrences...")
res = dataFrame.groupby(['Car', 'Place']).size()

下面是计算每个组合出现次数的代码 –

更多Pandas相关文章，请阅读：Pandas 教程

示例

# 导入库
import pandas as pd

# 初始化数据
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()

# 显示每个组合出现次数
print(res)

输出

这将产生以下输出 –

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