从某个短语开始到某个短语

Question

我有一些文本，其中一些实际上有预定义的模板，对分析没有任何价值。

我想使用regex 系统地删除template（通常由header text 和greetings 和closing text 等thank you 组成，这样我就可以专注于variable text .

header 和 closing 都可能具有可变文本，例如 variable location 或 variable staff name。所以text 1 可能有location 等于ABC 和staff name 等于Sofia。

have <- "Hello, thank you for contacting our Pizza Store, <variable location>. \n\r Please find below our available menu:\nMenu 1 USD 1.99\nMenu 2 USD 3.99\n\n\n Sincerely,\nThe Awesome Pizza Team\n<variable staff name>\nDelivering Pizza 24/7"

want <- "\nMenu 1 USD 1.99\nMenu 2 USD 3.99\n"


header <- "Hello, thank you for contacting our Pizza Store, <variable location>. \n\r Please find below our available menu:"

tail <- "\n\n Sincerely,\nThe Awesome Pizza Team\n<variable staff name>\nDelivering Pizza 24/7"

我目前的尝试如下。

# remove everything before 'menu'
gsub('(.*)menu:','', have)
# want to correct the above to
# remove everything that 
# starts with "Hello, thank you for contacting" up to "Please find our available menu"

# remove everything after Sincerely, inclusive
gsub('Sincerely.*','', have)
# want to correct the above to
# remove everything that 
# starts with "Sincerely,\nThe Awesome Pizza Team" up to "\nDelivering Pizza 24/7"

第二次尝试

# text
have <- "Hello, thank you for contacting our Pizza Store, <variable location>. \n\r Please find below our available menu:\nMenu 1 USD 1.99\nMenu 2 USD 3.99\n\n\n Sincerely,\nThe Awesome Pizza Team\n<variable staff name>\nDelivering Pizza 24/7"

# remove any text in between 'Hello, thank you for contacting` 
# up to 'Please find below our available menu:'
# and also the anchoring texts
(want <- gsub(pattern = '(Hello, thank you for contacting).*(Please find below our available menu:)',''
     , x = have))

# remove any text after `\n\n Sincerely,\nThe Awesome Pizza Team\n`, inclusive the text itself 
(want <- gsub(pattern = '\n\n Sincerely,\nThe Awesome Pizza Team\n.*',''
             , x = want))

Answer 1

一个选项可能是匹配菜单之前的所有行。然后捕获所有以 Menu 开头的连续行，并匹配以真诚开头的其余行。

在替换中使用捕获组 1。

^[\s\S]*?\R((?:Menu .*\R+)*)\s*Sincerely,[\s\S]*

模式匹配：

• ^字符串开始
• [\s\S]*?\R 尽可能匹配任何字符，后跟换行符
• ( 捕获第 1 组
  • (?:Menu .*\R+)* 重复匹配以Menu 开头的所有行并匹配换行符
• )关闭第一组
• \s* 匹配可选的空白字符
• Sincerely, 字面匹配
• [\s\S]* 匹配其余行

Regex demo | R demo

例子

have <- "Hello, thank you for contacting our Pizza Store, <variable location>. \n\r Please find below our available menu:\nMenu 1 USD 1.99\nMenu 2 USD 3.99\n\n\n Sincerely,\nThe Awesome Pizza Team\n<variable staff name>\nDelivering Pizza 24/7"
trimws(gsub('^[\\s\\S]*?\\R((?:Menu .*\\R+)*)\\s*Sincerely,[\\s\\S]*','\\1', have, perl = TRUE))

输出

[1] "Menu 1 USD 1.99\nMenu 2 USD 3.99"

---

更长一点的更精确的模式可能是：

 ^(?:(?!Menu ).*(?:\R(?!Menu ).*)*\R+)?(Menu .*(?:\RMenu .*)*)\R\s*Sincerely,[\s\S]*

Regex demo | R demo