Python基础-48-文本处理（逗号分隔值CSV）

前言

python自带模块csv可以将数据以csv格式输出到文件，也可以将csv数据读回

列表、元组数据写入和读取

【代码部分】

# coding:utf-8
import csv

# data也可以为列表
data = (
    ["1", "suner001", "b123456"],
    ["2", "suner002", "b123456"],
    ["3", "suner003", "b123456"],
    ["4", "suner004", "b123456"]
)

# 1）打开文件时，不加newline=""，会默认写入一行后隔一行再写入
# 2）csv.writer()需要一个打开的文件对象，返回一个writer对象
# 3）writer对象提供了writerow()方法，用来在打开的文件中逐行写入逗号分隔的数据
f = open("user_data.csv","w",encoding="utf-8",newline="")
writer = csv.writer(f)
for d in data:
    writer.writerow(d)
f.close()

# 4）csv.reader(f)需要一个打开的文件对象，返回一个reader可迭代对象对象
# 5）直接遍历取出数据即可
f = open("user_data.csv","r",encoding="utf-8")
reader = csv.reader(f)
for no, username, password in reader:
    print("编号：%s，账号：%s，密码：%s" % (no, username, password))
f.close()

【控制台输出结果】

【打开user_data.csv文件查看】

字典数据写入和读取

【代码部分】

# coding:utf-8
import csv

# data为字典的数据列表
data = [
    {"编号":1, "账号":"suner001", "密码":"b123456"},
    {"编号":2, "账号":"suner002", "密码":"b123456"},
    {"编号":3, "账号":"suner003", "密码":"b123456"},
    {"编号":4, "账号":"suner004", "密码":"b123456"}
]

# 1）csv.DictWriter(f, key_list)，需要一个打开的文件对象，和写入的头部（即第一行的key值），返回一个writer对象
# 2）dict_writer.writeheader()写入第一行的头数据（key）
# 3）循环字典列表数据，依次写入
f = open("user_data.csv", "w", encoding="utf-8", newline="")
key_list = [k for k in data[0].keys()]  # 取出key的列表
# print(key_list)  # ['密码', '编号', '账号']
dict_writer = csv.DictWriter(f, key_list)
dict_writer.writeheader()
for d in data:
    dict_writer.writerow(d)
f.close()

f = open("user_data.csv","r",encoding="utf-8")
dict_reader = csv.DictReader(f)
for row in dict_reader:
    print(row)

【控制台输出结果】

【打开user_data.csv文件查看】

优化代码

【代码部分】

# coding:utf-8
import csv

def list_data_write_csv(list_data,file_name):
    """list数据写入csv"""
    with open(file_name, "w", encoding="utf-8", newline="") as f:
        writer = csv.writer(f)
        for d in list_data:
            writer.writerow(d)
        return "数据全部写入成功"


def list_data_read_csv(file_name):
    """从csv中取出list数据"""
    with open(file_name, "r", encoding="utf-8") as f:
        reader = csv.reader(f)
        for no, username, password in reader:
            print ("编号：%s，账号：%s，密码：%s" % (no, username, password))
        return "数据全部读取完毕"

def dict_data_write_csv(dict_data,file_name):
    """dict数据写入csv"""
    with open(file_name, "w", encoding="utf-8", newline="") as f:
        key_list = [k for k in dict_data[0]]  # 取出key的列表
        dict_writer = csv.DictWriter(f, key_list)
        dict_writer.writeheader()
        for d in dict_data:
            dict_writer.writerow(d)
        return "数据全部写入成功"

def dict_data_read_csv(file_name):
    """从csv中取出dict数据"""
    with open(file_name, "r", encoding="utf-8") as f:
        dict_reader = csv.DictReader(f)
        for row in dict_reader:
            print(row)
        return "数据全部读取完毕"


list_data= [[1, "wang01", "123"], [2, "wang02", "123"], [3, "wang03", "123"]]
dict_data = [{"编号":1, "账号":"wang001", "密码":"123"}, {"编号":2, "账号":"wang002", "密码":"123"}]

print(list_data_write_csv(list_data,"user_info.csv"))
print(list_data_read_csv("user_info.csv"))

print(dict_data_write_csv(dict_data,"user_info01.csv"))
print(dict_data_read_csv("user_info01.csv"))

【控制台输出结果】

【打开csv文件查看】