从网站抓取数据并将其写入csv文件时，仅将最后一行写入该文件

Question

我正在使用python和漂亮的汤从网页中提取数据，并且可以正常工作。 问题是它没有将所有值插入到csv文件中。 就像如果我提取10个数据值而不是将第10个数据值转到csv文件一样，第9个数据值就没有。 所有10个数据值都显示在终端上，而不显示在csv文件中。

导入库

import csv

import urllib.request
from bs4 import BeautifulSoup



# specify the url
quote_page = "https://www.cardekho.com/Hyundai/Gurgaon/cardealers"
#quote_page = input("Enter Data Source Here : ")
page = urllib.request.urlopen(quote_page)



# parse the html using beautiful soup and store in variable `soup`
soup = BeautifulSoup(page, "lxml")


# Take out the <div> of name and get its value
delrname = soup.find_all('div', class_='deleadres')
for name in delrname:
    dname = name.find('div', class_="delrname").text # name
    print(dname)
for address in delrname:
    dadres = address.find('p').text
    print(dadres)
for mobile in delrname:
    dmobile = mobile.find('div', class_="clearfix").text
    print(dmobile)
for email in delrname:
    demail = email.find('div', class_="mobno").text
    print(demail)





#exorting data into csv file....
with open('result.csv',newline='') as f:
    r = csv.reader(f)
    data = [line for line in r]
with open('result.csv','w',newline='') as f:
    w = csv.writer(f)
    w.writerow(['NAME','ADDRES','MOBILE','EMAIL'])
    w.writerow([dname,dadres,dmobile,demail])**strong text**

Answer 1

在for循环中分配值时，将替换以前的值。 因此，在循环之外，您将获得最终值。

for number in 1, 2, 3:
    print(number) # prints 1, then 2, then 3
print(number) # prints only 3, since that was the final value.

在脚本中，使用单个for循环提取值并将数据行写入csv。

with open('result.csv','w',newline='') as f:
    w = csv.writer(f)
    w.writerow(['NAME','ADDRES','MOBILE','EMAIL']) # write header once
    entries = soup.find_all('div', class_='deleadres')
    for entry in entries: # loop over all `.deleadres` elements
        dname = entry.find('div', class_="delrname").text
        dadres = entry.find('p').text
        dmobile = entry.find('div', class_="clearfix").text
        demail = entry.find('div', class_="mobno").text
        w.writerow([dname,dadres,dmobile,demail]) # write data rows for each entry

Answer 2

您的错误是您只保存了循环中的最后一个值，因此没有获得所有值。

另一种方法是：

1）将循环中的值添加到列表中

2）将列表中的值添加到CSV

page = urllib.request.urlopen(quote_page)
# CREATE NEW LISTS
dname_list = list()
dadres_list = list()
dmobile_list = list()
demail_list = list()


# parse the html using beautiful soup and store in variable `soup`
soup = BeautifulSoup(page, "lxml")

# APPEND TO THE LIST
# Take out the <div> of name and get its value
delrname = soup.find_all('div', class_='deleadres')
for name in delrname:
    dname = name.find('div', class_="delrname").text # name
    print(dname)
    dname_list.append(dname)
for address in delrname:
    dadres = address.find('p').text
    print(dadres)
    dadres_list.append(dadres)
for mobile in delrname:
    dmobile = mobile.find('div', class_="clearfix").text
    print(dmobile)
    dmobile_list.append(dmobile)
for email in delrname:
    demail = email.find('div', class_="mobno").text
    print(demail)
    demail_list.append(demail)


#exorting data into csv file....
with open('result.csv',newline='') as f:
    r = csv.reader(f)
    data = [line for line in r]
with open('result.csv','w',newline='') as f:
    w = csv.writer(f)
    w.writerow(['NAME','ADDRES','MOBILE','EMAIL'])
    # TRAVERSE THROUGH THE LIST
    for i in range(len(dname)):
        try:
            w.writerow([dname_list[i],dadres_list[i],dmobile_list[i],demail_list[i]])
        except IndexError:
            print('')

PS：Haken的答案是一种更好的方法。 我只是想让您知道另一种方法。