自定义优先级输出失败及网页链接提取优先级异常问题求助

你的代码只是遍历原列表逐个打印，完全没改变输出顺序。要实现E、D、B、A的固定优先级输出，得先定义好目标顺序，再按这个顺序去原列表里匹配元素打印。

修改后的代码：

items = ['A','B','D','E']
# 定义优先级顺序
priority_order = ['E', 'D', 'B', 'A']

for item in priority_order:
    if item in items:
        print(item)

不管原列表元素顺序如何，都会严格按照priority_order的顺序输出存在的元素。

你的遍历逻辑有bug：遇到第一个不满足contact的元素时，只要它满足about就会直接赋值并跳出循环，根本没机会往后查找contact链接。比如页面里第一个a标签是about，程序就直接返回了，哪怕后面有contact链接。

正确逻辑是：先找contact链接，找到就终止查找；完全找不到contact时，再去查找about链接。

方案1：用CSS选择器直接定位（更简洁） #

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

links = [
    "http://www.innovaprint.com.sg/",
    "https://www.richardsonproperties.com/",
    "https://www.thepunctuationguide.com/",
    "http://www.knowledgeplatform.com/",
    "http://www.singaporeenterpriseassociation.com/",
    "https://www2.deloitte.com/sg/en.html"
]

headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:105.0) Gecko/20100101 Firefox/105.0'
}

for link in links:
    res = requests.get(link, headers=headers)
    soup = BeautifulSoup(res.text, "lxml")
    target_link = ''
    
    # 优先查找contact链接
    contact_item = soup.select_one('a[href]:contains("contact")')
    if contact_item:
        target_link = urljoin(link, contact_item['href'])
    else:
        # 没找到contact再找about
        about_item = soup.select_one('a[href]:contains("about")')
        if about_item:
            target_link = urljoin(link, about_item['href'])
    
    print(target_link)

方案2：分两次遍历（兼容性更强） #

如果:contains选择器不生效，就用两次遍历实现优先级：

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

links = [
    "http://www.innovaprint.com.sg/",
    "https://www.richardsonproperties.com/",
    "https://www.thepunctuationguide.com/",
    "http://www.knowledgeplatform.com/",
    "http://www.singaporeenterpriseassociation.com/",
    "https://www2.deloitte.com/sg/en.html"
]

headers = {
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:105.0) Gecko/20100101 Firefox/105.0'
}

for link in links:
    res = requests.get(link, headers=headers)
    soup = BeautifulSoup(res.text, "lxml")
    target_link = ''
    
    # 第一次遍历：找contact
    for item in soup.select("a[href]"):
        if "contact" in item.text.lower():
            target_link = urljoin(link, item['href'])
            break
    
    # 没找到contact，第二次遍历找about
    if not target_link:
        for item in soup.select("a[href]"):
            if "about" in item.text.lower():
                target_link = urljoin(link, item['href'])
                break
    
    print(target_link)

内容的提问来源于stack exchange，提问作者SMTH