pandas数据拼接merge

import pandas as pd
result_0 = pd.read_csv('2006年污染.csv',encoding = 'GBK')
result = result_0
for i in range(2007,2019):
    result_1 = pd.read_csv('{}年污染.csv'.format(i),encoding = 'GBK')
    result = pd.merge(result,result_1, on= ['养殖品种','养殖方式','省份编码'], how='outer') # 全连接
    print(i,result_1)
result.to_csv('合并.csv',encoding = 'GBK')