表格内容大致如下: 一共两列(Year | SIF )Year:2001 -2020

目的:求每一年对应的SIF 平均值

1 import pandas as pd 
 2 import numpy as np
 3 
 4 file = pd.read_csv('csv存放路径')
 5 a = []
 6 
 7 for year in range(2001,2021):
 8       sif = file[['SIF']][file['Year'] == year]
 9       mean_sif = np.average(sif)  # 一年sif平均
10       a.append(mean_sif)   # 将每一年的平均值放在一个数组里面
11 
12 # 新建csv
13 name = ['mean_sif']
14 new_file = pd.DataFrame(cloumns = name, data = a)
15 new_file.to_csv('新的csv存放地址',encoding = 'gbk')