csv文件的读取和写入

# -*- coding: utf-8 -*-

import csv

# 写入列表
headers = ["index", "a_name", "b_name"]
values = [[1, 'a', 'b'], [2, 'c', 'd'], [3, 'e', 'f']]
# 1. values 可迭代，list，tuple
# 2. 若结果中出现间隔空行，就加newline='' or 'w'-->'wb+'
with open('listdemo.csv', 'w', newline='') as f:
    writer = csv.writer(f)
    writer.writerow(headers)
    writer.writerows(values)

# 写入字典
headers = ['class', 'name', 'sex', 'height', 'year']
values = [{'class': 1, 'name': 'xiaoming', 'sex': 'male', 'height': 168, 'year': 23},
          {'class': 1, 'name': 'xiaohong', 'sex': 'female', 'height': 162, 'year': 22}]
#  若结果中出现间隔空行，就加newline='' or 'w'-->'wb+'
with open('dictdemo.csv', 'w', newline='') as f:
    f_csv = csv.DictWriter(f, headers)
    f_csv.writeheader()
    f_csv.writerows(values)

# 读取
# 按照列表形式取值
# 使用csv库的内置方法reader， 相当于xlrd读取excel，当然更方便了
with open("listdemo.csv", "r") as f:
    reader = csv.reader(f)     # reder是一个迭代器
    next(reader)               # 跳过表头/可选择不跳过
    for line in reader:
        print(line)

# 按照字典形式取值
with open("dictdemo.csv", "r") as f:
    reader = csv.DictReader(f)
    for line in reader:
        print(line, ' --- ', type(line))
        print({'name':line['name'], 'sex': line['sex']})