Python（csv 模块）

1、读取 csv 文件中的数据

• reader() 返回一个 reader 对象，利用该对象遍历 csv 文件中的行
• 从 csv 文件中读取的每一行都作为字符串列表返回

import csv

# data_info.csv 是文件名称
with open("data_info.csv","r") as f:
    data = csv.reader(f)
    for d in data:
        if d[0] == "username":    # 过滤第一行 title
            continue
        print(d)

# 结果如下
['admin', '123456']
['guest', '234567']

2、写入 csv 文件数据

• writer(myfile) 返回 writer 对象 mywriter
• writerow() 方法是一行一行写入，writerows 方法是一次写入多行
• 注意：如果文件 'data_info.csv' 事先存在，调用 writer 函数会先清空原文件中的文本，再执行 writerow/writerows 方法。

# 使用 writerow() 逐行写入

import csv

with open("data_info.csv","w",newline="") as f:
    mywrite = csv.writer(f)
    mywrite.writerow(["username","password"])
    mywrite.writerow(["admin","123456"])
    mywrite.writerow(["guest","234567"])

# 使用 writerows() 批量写入

import csv

with open("data_info.csv","w",newline="") as f:
    mywrite = csv.writer(f)
    # 每行数据放在一个数组中
    data_list = [["username","password"],["admin","123456"],["guest","234567"]]
    mywrite.writerows(data_list)