如何使用正则表达式 re.compile 创建捕获组？

Question

可以成功找到字符串，但无法将匹配对象分成正确的组

完整的字符串如下：

 Technology libraries: Techlibhellohellohello

（都在一行上）。我想要做的是在文件中找到这一行（有效），但是当我想添加到字典时，我只想添加“技术库”部分而不是其他所有内容。我想使用 .group() 并指定哪个组，但只有 Techlibhellohellohello 似乎作为组（1）弹出，没有其他组出现。此外，技术库之前还有前导空白

要匹配的对象

is_startline_1 = re.compile(r" Technology libraries: (.*)$")

匹配的行

startline1_match = is_startline_1.match(line)

添加到字典

bookmark_dict['context']        = startline1_match.group(1)

所需的输出是 .groups(1) 或 .groups(2) 包含“技术库”

Answer 1

在这里，我们可能只想用捕获组包装第一部分：

# coding=utf8
# the above tag defines encoding for this document and is for Python 2.x compatibility

import re

regex = r"(Technology libraries: )(.*)$"

test_str = "Technology libraries: Techlibhellohellohello"

subst = "\\1\\n\\2"

# You can manually specify the number of replacements by changing the 4th argument
result = re.sub(regex, subst, test_str, 0, re.MULTILINE)

if result:
    print (result)

# Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

这个 JavaScript 演示展示了捕获组的工作原理：

const regex = /(Technology libraries: )(.*)$/gm;
const str = `Technology libraries: Techlibhellohellohello`;
const subst = `\n$1\n$2`;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log('Substitution result: ', result);

正则表达式

如果这不是您想要的表达方式，您可以在regex101.com 中修改/更改您的表达方式。

 (Technology libraries: )(.*)

正则表达式电路

您还可以在jex.im 中可视化您的表达式：

---

如果您希望删除 : 和空格，您只需添加一个中间捕获组即可：

Demo

(Technology libraries)(:\s+)(.*)

Python 代码

# coding=utf8
# the above tag defines encoding for this document and is for Python 2.x compatibility

import re

regex = r"(Technology libraries)(:\s+)(.*)"

test_str = ("Technology libraries: Techlibhellohellohello\n"
    "Technology libraries:     Techlibhellohellohello")

subst = "\\1\\n\\3"

# You can manually specify the number of replacements by changing the 4th argument
result = re.sub(regex, subst, test_str, 0, re.MULTILINE)

if result:
    print (result)

# Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

JavaScript 演示

const regex = /(Technology libraries)(:\s+)(.*)/gm;
const str = `Technology libraries: Techlibhellohellohello
Technology libraries:     Techlibhellohellohello`;
const subst = `\n$1\n$3`;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log('Substitution result: ', result);

---

如果您想捕获“技术库”之前的空格，您可以简单地将它们添加到捕获组：

^(\s+)(Technology libraries)(:\s+)(.*)$

Demo

Python 测试

# coding=utf8
# the above tag defines encoding for this document and is for Python 2.x compatibility

import re

regex = r"^(\s+)(Technology libraries)(:\s+)(.*)$"

test_str = ("    Technology libraries: Techlibhellohellohello\n"
    "       Technology libraries:     Techlibhellohellohello")

subst = "\\2\\n\\4"

# You can manually specify the number of replacements by changing the 4th argument
result = re.sub(regex, subst, test_str, 0, re.MULTILINE)

if result:
    print (result)

# Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

JavaScript 演示

const regex = /^(\s+)(Technology libraries)(:\s+)(.*)$/gm;
const str = `    Technology libraries: Techlibhellohellohello
       Technology libraries:     Techlibhellohellohello`;
const subst = `$2\n$4`;

// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);

console.log('Substitution result: ', result);