CSV的简单用法

　　读文件

import csv
with open('test.csv','rb') as myFile:
    lines=csv.reader(myFile)
    for line in lines:
        print line  

程序输出：

['1', '2']
['3', 'a']
['4', 'b']

　　写文件

with open(r'C:\Users\asus\Desktop\frank.csv','w') as myFile:
    writer = csv.writer(myFile)
    writer.writerow(['frank', 'yangchao'])
    writer.writerows([('Bob','Tom'), ('liuwei', 'liuyong')])

　　注意用csv的默认写入时候，写完一行会自动空行后再写入，但添加中间的参数 newline='' 表示写完一行接着写第二行，中间不空行。同时参数‘r’，‘w’表示读取的字符，‘rb’, 'wb'表示读写的字节

with open(r'C:\Users\asus\Desktop\frank.csv','w', newline='') as myFile:
    writer = csv.writer(myFile)
    writer.writerow(['frank', 'yangchao'])
    writer.writerows([('Bob','Tom'), ('liuwei', 'liuyong')])

csv.DictWriter 与DictReader 读写文件

读文件

文件如下：

DictReader会将第一行的内容（类标题）作为key值，第二行开始才是数据内容，第一列的key值为name，第二列的key值为class：

import csv
with open(r'C:\Users\asus\Desktop\frank.csv','r') as myFile:
    reader = csv.DictReader(myFile)
    for row in reader:
        print(row['name'], row['class'])

输出结果：
frank 135
tom 134
bob 141
ailsa 152

写文件

import csv
with open(r'C:\Users\asus\Desktop\frank.csv','w',newline='') as myFile:
    writer = csv.DictWriter(myFile, fieldnames=['name', 'address']) # 这里注意，fieldname列表中的字段为需要存入的字典的key，存入之后就存入key所对应的value
    writer.writeheader()
    writer.writerows([{'name':'Tom','address':'American'}, {'name':'Bob', 'address':'China'}])

注意：writer.writeheader() 语句的作用是将 fieldnames=['name', 'address'] 中定义的标题（key）写入到首行

效果如下：