爬虫16-csv用法

1.读取

import csv
def read_csv_demo1():
    with open('stock.csv','r') as fp:
        # reader是一个迭代器
        reader=csv.reader(fp)
        next(reader)
        for x in reader:
            name=x[3]
            volumn=x[-1]
            print({"name":name,"volumn":volumn})

def read_csv_demo2():
    with open('stock.csv', 'r') as fp:
        # 使用DictReader创建的reader对象
        # 不会包含标题那行的数据
        # reader是一个迭代器，遍历这个迭代器，返回来的是一个字典。
        reader=csv.DictReader(fp)
        for x in reader:
            print(x["secShortName"])
if __name__ == '__main__':
    read_csv_demo2()

　　

2.写入

#encoding: utf-8

import csv

def write_csv_demo1():
    headers = ['username', 'age', 'height']
    values = [
        ('張三', 18, 180),
        ('李四', 19, 190),
        ('王五', 20, 160)
    ]

    with open('classroom.csv', 'w', encoding='utf-8', newline='') as fp:
        writer = csv.writer(fp)
        writer.writerow(headers)
        writer.writerows(values)


def write_csv_demo2():
    headers = ['username', 'age', 'height']
    values = [
        {'username':'张三','age':18,'height':180},
        {'username':'李四','age':19,'height':190},
        {'username':'王五','age':20,'height':160}
    ]
    with open('classroo1.csv','w',encoding='utf-8',newline='') as fp:
        writer = csv.DictWriter(fp,headers)
        # 写入表头数据的时候，需要调用writeheader方法
        writer.writeheader()
        writer.writerows(values)


if __name__ == '__main__':
    write_csv_demo2()