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【python3】中str转成bytes类型后用csv.writerow()写入csv文件仍然出错

2017-09-06 19:23:22  来源:网友分享

根本原因是Python版本问题python2.x中要求用‘wb’,python3.x中要求用'w'

首先声明:CSV文件是可以用二进制模式写入的

python文档(传送门)关于CSV的一个用法示例:


文件打开的mode是“wb”

with open('rent.csv','wb') as csv_file:

且与Pythone3里面字符串和二进制数据是两种类型,所以要将str类型转换成bytes类型

出错部分代码

#把str类型的housetitle、house_location、house_money编码成bytes类型
house_title = house_title.encode("utf8")
house_location = house_location.encode("utf8")
house_money = house_money.encode("utf8")
house_url = house_url.encode("utf8")

#查看house_title等的类型
print(type(house_title),type(house_location),type(house_money),type(house_url))

# 向csv文件写入数据
with open('rent.csv','wb') as csv_file:
    csv_writer = csv.writer(csv_file,delimiter=',')
    csv_writer.writerow([house_title, house_location, house_money, house_url])

错误提示

可以看到这里输出的house_title, house_location, house_money, house_url类型都是bytes

然而下面还是报了类型错误

Please Tell Me Why?

主程序全部代码

from bs4 import BeautifulSoup
from urllib.parse import urljoin
import requests
import csv

url = "http://nj.58.com/pinpaigongyu/pn/{page}/?minprice=1000_1500"

page = 1

print("fetch: ", url.format(page=page))

# 抓取目标页面
response = requests.get(url.format(page=page))

# 创建一个BeautifulSoup对象
html = BeautifulSoup(response.text, "lxml") 

# 获取class=list下的所有li元素
house_list = html.select(".list > li")

for house in house_list:
    house_title = house.select("h2")[0].string
    house_url = urljoin(url, house.select("a")[0]["href"])
    
    house_info_list = house_title.split()
    
    house_location = house_info_list[1]
    house_money = house.select(".money")[0].select("b")[0].string

    #把str类型的housetitle、house_location、house_money编码成bytes类型
    house_title = house_title.encode("utf8")
    house_location = house_location.encode("utf8")
    house_money = house_money.encode("utf8")
    house_url = house_url.encode("utf8")

    #查看house_title等的类型
    print(type(house_title),type(house_location),type(house_money),type(house_url))
    
    # 向csv文件写入数据
    with open('rent.csv','wb') as csv_file:
        csv_writer = csv.writer(csv_file,delimiter=',')
        csv_writer.writerow([house_title, house_location, house_money, house_url])

     #用with的写法就不用写关闭文件的csv_file.close()语句了

解决方案

先看了大概,问题很多~

#csv_file = open("rent.csv","wb") # 这句删除,重复了

with open('rent.csv','w') as csv_file:
    csv_writer = csv.writer(csv_file,delimiter=',')
    for house in house_list: # 在这里写csv
        #。。。。。。
        csv_writer.writerow([house_title, house_location, house_money, house_url])

更新一点

csv 是文本格式的文件,不支持二进制的写入,所以不要用二进制模式打开文件,数据也不必转成bytes。

再更

根本原因是楼主看错文档,导致了理解有误~