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Python技巧分享之groupby基础用法详解_python_

2023-05-25 352人已围观

简介 Python技巧分享之groupby基础用法详解_python_

模拟数据

import pandas as pd import numpy as np 
employees = ["小明","小周","小孙","小王","小张"] # 5位员工 time = ["上半年", "下半年"] df=pd.DataFrame({ "employees":np.random.choice(employees,10), # 在员工中重复选择10次 # 另一种写法 #"employees":[employees[x] for x in np.random.randint(0,len(employees),10)], "time":np.random.choice(time,10), "salary":np.random.randint(800,1000,10), # 800-1000之间的薪资选择10个数值 "score":np.random.randint(6,12,10) # 6-11的分数选择10个 }) df 

groupby+单个字段+单个聚合

求解每个人的总薪资金额:

total_salary = df.groupby("employees")["salary"].sum().reset_index() total_salary 

使用agg也能够实现上面的效果:

df.groupby("employees").agg({"salary":"sum"}).reset_index() 

df.groupby("employees").agg({"salary":np.sum}).reset_index() 

groupby+单个字段+多个聚合

求解每个人的总薪资金额和薪资的平均数

方法1:使用groupby+merge

mean_salary = df.groupby("employees")["salary"].mean().reset_index() mean_salary 

然后将上面的两个结果进行组合;在合并之前为了字段的名字更加的直观,我们重命名下:

total_salary.rename(columns={"employees":"total_salary"}) mean_salary.columns = ["employees","mean_salary"] 
total_mean = total_salary.merge(mean_salary) total_mean 

方法2:使用groupby+agg

total_mean = df.groupby("employees")\ .agg(total_salary=("salary", "sum"), mean_salary=("salary", "mean"))\ .reset_index() total_mean 

groupby+多个字段+单个聚合

针对多个字段的同时聚合:

df.groupby(["employees","time"])["salary"].sum().reset_index() 

# 使用agg来实现 df.groupby(["employees","time"]).agg({"salary":"sum"}).reset_index() 

groupby+多个字段+多个聚合

使用的方法是:

agg(’新列名‘=(’原列名‘, ’统计函数/方法‘))

df.groupby(["employees","time"])\ .agg(total_salary=("salary", "sum"), mean_salary=("salary", "mean"), total_score=("score", "sum") )\ .reset_index() 

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