如何在Python中提取两个字符间的子串，从HTML字符串中获取颜色名

方法1：使用正则表达式精准匹配（推荐） #

因为所有颜色都在href以/colours/开头的<a>标签内，直接用正则匹配可以一步得到结果，避免提取到多余内容：

import re
import html

# 原始转义字符串
raw_str = '''<p><topic url="car-colours">Toyota Camry</topic> has <a href="/colours/dark-red">Dark Red</a><span> (2020)</span>, <a href="/colours/pearl-white">Pearl White</a><span> (2016 - 2017)'''

# 还原HTML转义字符为正常符号
processed_str = html.unescape(raw_str)

# 正则匹配a标签内的颜色文本，捕获组对应颜色名
toyota_camry_colours = re.findall(r'<a href="/colours/[^"]+">([^<]+)</a>', processed_str)

print(toyota_camry_colours)
# 输出：['Dark Red', 'Pearl White']

方法2：按指定规则提取>和<之间的内容后筛选 #

如果你需要严格按照提取>和<中间子串的思路实现，可参考以下代码：

import html

raw_str = '''<p><topic url="car-colours">Toyota Camry</topic> has <a href="/colours/dark-red">Dark Red</a><span> (2020)</span>, <a href="/colours/pearl-white">Pearl White</a><span> (2016 - 2017)'''
processed_str = html.unescape(raw_str)

# 提取所有><之间的非空内容
parts = []
start = 0
while True:
    start = processed_str.find('>', start)
    if start == -1:
        break
    start += 1
    end = processed_str.find('<', start)
    if end == -1:
        break
    part = processed_str[start:end].strip()
    if part:
        parts.append(part)
    start = end

# 过滤掉非颜色的冗余内容
exclude_set = {'Toyota Camry', 'has', '(2020)', ',', '(2016 - 2017)'}
toyota_camry_colours = [p for p in parts if p not in exclude_set]

print(toyota_camry_colours)
# 输出：['Dark Red', 'Pearl White']

内容的提问来源于stack exchange，提问作者markovv.sim