正则表达式 - 用逗号分割字符串，跳过平衡括号之间的任何内容

Question

需要在 R - Perl 中编写一个正则表达式，它会在逗号 '' 上拆分字符串，但会跳过圆括号之间的所有逗号实例。挑战在于确保括号是平衡的，即闭括号映射回其开括号。

在下面的正则表达式代码中，一切正常，除非您注意到 - 括号不平衡，内端括号正在考虑用于外部开始括号

text <- "PEANUTS (PEANUTS, PEANUT OIL AND/OR COTTONSEED OIL AND/OR CANOLA OIL AND/OR SOYBEAN OIL, SALT), GOLDEN RAISINS (RAISINS, SULFUR DIOXIDE), DRIED CRANBERRIES (CRANBERRIES, SUGAR, CITRIC ACID, SUNFLOWER OIL (PROCESSING AID), ELDERBERRY JUICE CONCENTRATE (COLOR)), ALMONDS (ALMONDS, PEANUT OIL AND/OR COTTONSEED OIL AND/OR CANOLA OIL AND/OR SOYBEAN OIL, SALT), MACADAMIAS (MACADAMIAS, MALTODEXTRIN, SALT)"

strsplit(text, '\\([^*)^)]*\\)(*SKIP)(*F)|\\,', perl=T)

使用上述正则表达式代码，蔓越莓干 未正确拆分。请参考此处的输出截图：Regex Code Output

这里的任何帮助将不胜感激..谢谢！

Answer 1

对this question 的已接受答案的编辑似乎可以完成这项工作。我只是在开头添加了[[:alpha:][:space:]]*。

pat <- '[[:alpha:][:space:]]*\\(((?>[^()]+)|(?R))*\\)'
regmatches(text, gregexpr(pat, text, perl = TRUE))
#[[1]]
#[1] "PEANUTS (PEANUTS, PEANUT OIL AND/OR COTTONSEED OIL AND/OR #CANOLA OIL AND/OR SOYBEAN OIL, SALT)"                            
#[2] " GOLDEN RAISINS (RAISINS, SULFUR DIOXIDE)"                                                                                 
#[3] " DRIED CRANBERRIES (CRANBERRIES, SUGAR, CITRIC ACID, SUNFLOWER #OIL (PROCESSING AID), ELDERBERRY JUICE CONCENTRATE (COLOR))"
#[4] " ALMONDS (ALMONDS, PEANUT OIL AND/OR COTTONSEED OIL AND/OR #CANOLA OIL AND/OR SOYBEAN OIL, SALT)"                           
#[5] " MACADAMIAS (MACADAMIAS, MALTODEXTRIN, SALT)" 

Answer 2

你可以使用

strsplit(text, "(\\((?:[^()]++|(?1))*\\))(*SKIP)(*F)|,", perl=TRUE)
# => [[1]]
[1] "PEANUTS (PEANUTS, PEANUT OIL AND/OR COTTONSEED OIL AND/OR CANOLA OIL AND/OR SOYBEAN OIL, SALT)"                            
[2] " GOLDEN RAISINS (RAISINS, SULFUR DIOXIDE)"                                                                                 
[3] " DRIED CRANBERRIES (CRANBERRIES, SUGAR, CITRIC ACID, SUNFLOWER OIL (PROCESSING AID), ELDERBERRY JUICE CONCENTRATE (COLOR))"
[4] " ALMONDS (ALMONDS, PEANUT OIL AND/OR COTTONSEED OIL AND/OR CANOLA OIL AND/OR SOYBEAN OIL, SALT)"                           
[5] " MACADAMIAS (MACADAMIAS, MALTODEXTRIN, SALT)" 

查看regex demo 和online R demo。

详情

• (\\((?:[^()]++|(?1))*\\)) - 一个捕获组 #1，它捕获
  • \\( - 一个 ( 字符
  • (?:[^()]++|(?1))* - 除了( 和)（[^()]++）或（|）整个组 1 模式（递归以匹配所有嵌套级别）之外，出现 0 次或多次 1+ 字符李>
  • \\) - 一个 ) 字符
• (*SKIP)(*F) - 这两个动词使引擎跳过当前匹配的字符串并继续在该文本之后立即查找下一个匹配项。
• | - 或
• , - 逗号。