Python正则表达式匹配一行并替换[关闭]

Question

需要帮助python regex。 （用于文件比较程序）

解析参数以“+”，“ - ”和“'开头的文件。 （'+ < - SPACE->'，' - < - SPACE->'，'< - SPACE - > < - SPACE->'）。我需要用一些文字替换它。例子

我想将其替换为： -

Answer 1

虽然Gillespie的解决方案非常棒，但我会说为了灵活性使用正则表达式。

我在下面提供一些示例和用例

.

这采取的形式

re.sub(r'[+\-\s]{,4}((?:YOUR_QUERY_HERE[\s]*[\S]+(?=[\s]+|$)))', r'\n<p class="blue">\1</p>', string)

在哪里用你想要的东西取代YOUR_QUERY_HERE

所以使用This[\s]*is[\s]*line[\s]*[\S]+你可以得到

>>> import re

>>> string = '''+ This is line one
- This is line two
This is line three'''

>>> capture = re.sub(r'[+\-\s]{,4}?((?:This[\s]*is[\s]*line[\s]*[\S]+(?=[\s]+|$)))', r'\n<p class="blue">\1</p>', string)
>>> print(capture)

<p class="blue">This is line one</p>
<p class="blue">This is line two</p>
<p class="blue">This is line three</p>

.

如果你有一个行变化的文件，你可以像这样定位特定的组

>>> import re

>>> string = '''+ This is line one
- This is line two
  This is line three
+ Bobby has hobbies
- Meg is a brain
+ The pool hurts
  Manny is love
  This is line four
- The end of the world
- This is line five
+ This is line six
  Is upon us'''


>>> capture = re.sub(r'[+\-\s]{,4}?((?:This[\s]*is[\s]*line[\s]*[\S]+(?=[\s]+|$)))', r'\n<p class="blue">\1</p>', string)
>>> print(capture)

<p class="blue">This is line one</p>
<p class="blue">This is line two</p>
<p class="blue">This is line three</p>
+ Bobby has hobbies
- Meg is a brain
+ The pool hurts
  Manny is love
<p class="blue">This is line four</p>
- The end of the world
<p class="blue">This is line five</p>
<p class="blue">This is line six</p>
  Is upon us

Answer 2

你不需要正则表达式。尝试类似的东西：

with open("myfile.txt") as f:
  for line in f:
    if line[0] == "+":
      print('<p class="blue">{}</p>'.format(line[1:].strip()))
    elif line[0] == "-":
      print('<p class="green">{}</p>'.format(line[1:].strip()))
    else:
      print('<p class="normal">{}</p>'.format(line))

见例子：https://repl.it/repls/SameMintyDigit

编辑：Per @ Felk建议提高可读性：

def printLine(color, line):
  print(f'<p class="{color}">{line}</p>')

with open("myfile.txt") as f:
  for line in f:
    if line[0] == "+":
      printLine("blue", line[1:].strip())
    elif line[0] == "-":
      printLine("green", line[1:].strip())
    else:
      printLine("normal", line)