Python regex match a line and replace [closed]

问题:

Need help with python regex. (Using for file compare program)

Parsing a file with parameters starting with '+ ', '- ' and ' '. ('+<-SPACE->', '-<-SPACE->', '<-SPACE-><-SPACE->'). and I need to replace it with some text. Examples

I want to replace it to :--

回答1:

Although Gillespie's solution is awesome, I'd say for flexibility's sake use regex.

I provide some examples and use cases below

.

This takes the form

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

where you replace YOUR_QUERY_HERE with what you desire

So using This[\s]*is[\s]*line[\s]*[\S]+ you can get

>>> 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>

.

And if you have a file where the lines vary you can target the specific group like so

>>> 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

回答2:

You don't need regex for this. Try something like:

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))

See example: https://repl.it/repls/SameMintyDigit

Edit: Per @Felk's suggestion for increased readability:

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)