Python regex从orgmode文件获取项

Question

我有以下组织模式语法：

** Hardware [0/1]
 - [ ] adapt a programmable motor to a tripod to be used for panning 
** Reading - Technology [1/6]
 - [X] Introduction to Networking - Charles Severance
 - [ ] A Tour of C++ - Bjarne Stroustrup
 - [ ] C++ How to Program - Paul Deitel
 - [X] Computer Systems - Randal Bryant
 - [ ] The C programming language - Brian Kernighan
 - [ ] Beginning Linux Programming -Matthew and Stones
** Reading - Health [3/4]
 - [ ] Patrick McKeown - The Oxygen Advantage
 - [X] Total Knee Health - Martin Koban
 - [X] Supple Leopard - Kelly Starrett
 - [X] Convict Conditioning 1 and 2  

我想提取项目，例如：

 getitems "Hardware"

我应该得到：

  - [ ] adapt a programmable motor to a tripod to be used for panning  

如果我要求“阅读-健康”，我应该得到：

 - [ ] Patrick McKeown - The Oxygen Advantage
 - [X] Total Knee Health - Martin Koban
 - [X] Supple Leopard - Kelly Starrett
 - [X] Convict Conditioning 1 and 2 

我使用以下模式：

   pattern = re.compile("\*\* "+ head + " (.+?)\*?$", re.DOTALL)

请求“阅读技术”时的输出是：

  - [X] Introduction to Networking - Charles Severance
  - [ ] A Tour of C++ - Bjarne Stroustrup
  - [ ] C++ How to Program - Paul Deitel
  - [X] Computer Systems - Randal Bryant
  - [ ] The C programming language - Brian Kernighan
  - [ ] Beginning Linux Programming -Matthew and Stones
   ** Reading - Health [3/4]
  - [ ] Patrick McKeown - The Oxygen Advantage
  - [X] Total Knee Health - Martin Koban
  - [X] Supple Leopard - Kelly Starrett
  - [X] Convict Conditioning 1 and 2  

我也试过：

   pattern = re.compile("\*\* "+ head + " (.+?)[\*|\z]", re.DOTALL)

最后一个可以很好地处理除最后一个之外的所有头。你知道吗

请求“阅读-健康”时的输出：

 - [ ] Patrick McKeown - The Oxygen Advantage
 - [X] Total Knee Health - Martin Koban
 - [X] Supple Leopard - Kelly Starrett

如你所见，它与最后一行不符。你知道吗

我使用的是python2.7和findall。你知道吗

Answer 1

如果确定项目中不存在字符*，则可以使用：

re.compile(r"\*\* "+head+r" \[\d+/\d+\]\n([^*]+)\*?")

Answer 2

你可以通过

import re

string = """
** Hardware [0/1]
 - [ ] adapt a programmable motor to a tripod to be used for panning 
** Reading - Technology [1/6]
 - [X] Introduction to Networking - Charles Severance
 - [ ] A Tour of C++ - Bjarne Stroustrup
 - [ ] C++ How to Program - Paul Deitel
 - [X] Computer Systems - Randal Bryant
 - [ ] The C programming language - Brian Kernighan
 - [ ] Beginning Linux Programming -Matthew and Stones
** Reading - Health [3/4]
 - [ ] Patrick McKeown - The Oxygen Advantage
 - [X] Total Knee Health - Martin Koban
 - [X] Supple Leopard - Kelly Starrett
 - [X] Convict Conditioning 1 and 2  
 """

def getitems(section):
    rx = re.compile(r'^\*{2} ' + re.escape(section) + r'.+[\n\r](?P<block>(?:(?!^\*{2})[\s\S])+)', re.MULTILINE)
    try:
        items = rx.search(string)
        return items.group('block')
    except:
        return None

items = getitems('Reading - Technology')
print(items)

看看working on ideone.com。

---

代码的核心是（浓缩的）表达式：

^\*{2}.+[\n\r]       # match the beginning of the line, followed by two stars, anything else in between and a newline
(?P<block>           # open group "block"
    (?:              # non-capturing group
        (?!^\*{2})   # a neg. lookahead, making sure no ** follows at the beginning of a line
        [\s\S]       # any character...
    )+               # ...at least once
)                    # close group "block"

在实际代码的**之后插入搜索字符串。请参见regex101.com上的Reading - Technology演示。

---

作为后续操作，您也可以只返回所选值，如下所示：

def getitems(section, selected=None):
    rx = re.compile(r'^\*{2} ' + re.escape(section) + r'.+[\n\r](?P<block>(?:(?!^\*{2})[\s\S])+)', re.MULTILINE)
    try:
        items = rx.search(string).group('block')
        if selected:
            rxi = re.compile(r'^ - \[X\]\ (.+)', re.MULTILINE)
            try:
                selected_items = rxi.findall(items)
                return selected_items
            except:
                return None
         return items
    except:
        return None

items = getitems('Reading - Health', selected=True)
print(items)

Answer 3

不确定整场比赛都需要正则表达式。我只需要使用正则表达式来匹配**行，然后返回行，直到看到下一行**。你知道吗

像这样的

pattern = re.compile("\*\* "+ head)

start = False
output = []
for line in my_file:
    if pattern.match(line):
         start = True
         continue
    elif line.startswith("**"): # but doesn't match pattern
        break

    if start:
        output.append(line)

# now `output` should have the lines you want