Python - IndexError：列表索引超出范围 - 不工作

Question

这是我的scrap.py代码

from bs4 import BeautifulSoup as soup
from urllib.request import urlopen as uReq

website = "https://houston.craigslist.org/search/cta"

uClient = uReq(website)
page_html = uClient.read()
uClient.close()

soup_html = soup(page_html, "html.parser")
result_html = soup_html.findAll("p", {"class":"result-info"})

filename = "products.csv"

f = open(filename, "w", encoding='utf8')
headers = "car_name, price\n"
f.write(headers)

for container in result_html:   
    carname = container.a.text

    price_container = container.findAll('span', {'class':'result-price'})
    price = price_container[0].text

    f.write(carname + "," + price + "\n")

f.close()

在终端上，它工作正常但是当我循环它时，它给出以下错误..

Traceback (most recent call last):
  File "scrap.py", line 23, in <module>
    price = price_container[0].text.splitlines()
IndexError: list index out of range

请帮忙。谢谢

Answer 1

试试下面的一个。它将获取所有物品和价格，并处理IndexError，如果有的话。

from bs4 import BeautifulSoup
from urllib.request import urlopen

response = urlopen("https://houston.craigslist.org/search/cta")
soup_html = BeautifulSoup(response.read(), "html.parser")
for container in soup_html.find_all("p", {"class":"result-info"}):   
    carname = container.find_all("a")[0].text
    try:
        price = container.find_all('span', {'class':'result-price'})[0].text
    except IndexError:
        price = ""
    print(carname,price)

我试图缩短你的代码，让它看起来更好。

Answer 2

这是因为有些汽车没有价格，例如this one。如果没有价格，你可以把价格放到unknown：

price_container = container.findAll('span', {'class':'result-price'})
if len(price_container) > 0:
    price = price_container[0].text
else:
    price = 'unknown'

或者你可以跳过没有价格的那些，所以他们不会被写入文件：

price_container = container.findAll('span', {'class':'result-price'})
if len(price_container) == 0:
   continue
price = price_container[0].text

我该如何按价格对其进行排序？

results = []
for container in result_html:   
    carname = container.a.text

    price_container = container.findAll('span', {'class':'result-price'})
    if len(price_container) == 0:
        continue

    price = price_container[0].text.strip('$')
    results.append((int(price), carname))

for price, carname in sorted(results):
    f.write("{}, {}\n".format(carname, price))

f.close()