关于csv.reader（）的用法

Posted 2020-11-01 glcat

转自https://blog.csdn.net/swc5285018/article/details/78967958
import json
import csv
import os


def csv_process(filepath):
    with open(filepath,mode=‘r‘,encoding=‘utf-8‘,newline=‘‘) as f:
        #此处读取到的数据是将每行数据当做列表返回的
        reader = csv.reader(f)
        for row in reader:
            #此时输出的是一行行的列表
            # print(row)
            print(‘+‘.join(row))

def json_process(filepath):
    with open(filepath,mode=‘r‘,encoding=‘utf-8‘) as f:
        city_list = json.load(f)
        print(city_list)

def main():
    filepath = input(‘请输入文件名称：‘)
    name,index = os.path.splitext(filepath)
    if index == ‘.json‘:
        json_process(filepath)
    elif index == ‘.csv‘:
        csv_process(filepath)
if __name__ == ‘__main__‘:
    main()

这是csv文件

time_point,aqi,quality,primary_pollutant,position_name,area,station_code,pm2_5,pm2_5_24h
2017-07-29T14:00:00Z,44,优,,天坛,北京,1004A,24,30
2017-07-29T14:00:00Z,46,优,,农展馆,北京,1005A,28,38
2017-07-29T14:00:00Z,47,优,,万寿西宫,北京,1001A,32,33
2017-07-29T14:00:00Z,50,优,,古城,北京,1012A,35,27
2017-07-29T14:00:00Z,54,良,细颗粒物(PM2.5),海淀区万柳,北京,1007A,38,28
2017-07-29T14:00:00Z,57,良,细颗粒物(PM2.5),东四,北京,1003A,40,36
2017-07-29T14:00:00Z,58,良,细颗粒物(PM2.5),官园,北京,1006A,41,32
2017-07-29T14:00:00Z,58,良,"颗粒物(PM2.5),颗粒物(PM10)",,北京,,40,29
2017-07-29T14:00:00Z,60,良,细颗粒物(PM2.5),奥体中心,北京,1011A,43,32
2017-07-29T14:00:00Z,63,良,颗粒物(PM10),定陵,北京,1002A,37,20
2017-07-29T14:00:00Z,77,良,颗粒物(PM10),昌平镇,北京,1010A,46,20
2017-07-29T14:00:00Z,80,良,臭氧1小时,怀柔镇,北京,1009A,48,21
2017-07-29T14:00:00Z,102,轻度污染,细颗粒物(PM2.5),顺义新城,北京,1008A,76,38

 

reader = csv.reader(f) 此时reader返回的值是csv文件中每行的列表，将每行读取的值作为列表返回

for row in reader:

    print(row)

此时运行程序打印出来的row如下：

[‘time_point‘, ‘aqi‘, ‘quality‘, ‘primary_pollutant‘, ‘position_name‘, ‘area‘, ‘station_code‘, ‘pm2_5‘, ‘pm2_5_24h‘]
[‘2017-07-29T14:00:00Z‘, ‘44‘, ‘优‘, ‘‘, ‘天坛‘, ‘北京‘, ‘1004A‘, ‘24‘, ‘30‘]
[‘2017-07-29T14:00:00Z‘, ‘46‘, ‘优‘, ‘‘, ‘农展馆‘, ‘北京‘, ‘1005A‘, ‘28‘, ‘38‘]
[‘2017-07-29T14:00:00Z‘, ‘47‘, ‘优‘, ‘‘, ‘万寿西宫‘, ‘北京‘, ‘1001A‘, ‘32‘, ‘33‘]

为一个个列表

如果我们想用另外一种方式展示可以用如下方法：

print(‘, ‘.join(row))

展示如下：

time_point,aqi,quality,primary_pollutant,position_name,area,station_code,pm2_5,pm2_5_24h
2017-07-29T14:00:00Z,44,优,,天坛,北京,1004A,24,30
2017-07-29T14:00:00Z,46,优,,农展馆,北京,1005A,28,38
2017-07-29T14:00:00Z,47,优,,万寿西宫,北京,1001A,32,33
2017-07-29T14:00:00Z,50,优,,古城,北京,1012A,35,27

上面的用法举个简单例子：

l = [‘a‘,‘b‘,‘c‘,‘d‘]

print(‘+‘.join(l))

输出结果为：

[a+b+c+d]