Question

需要在R-Perl中编写一个正则表达式，该正则表达式将在逗号'，上拆分字符串，但是在圆括号之间跳过所有逗号实例。面临的挑战是确保括号之间的平衡，即右括号映射回到其右括号。

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，否则考虑将内端括号用作外起始括号

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)

使用上面的正则表达式代码，未正确分割干蔓越莓。请在此处参考输出屏幕截图：Regex Code Output

这里的任何帮助将不胜感激。。谢谢！

Answer 1

您可以使用

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)"

请参见regex demo和online R demo。

详细信息

(\\((?:[^()]++|(?1))*\\))-捕获＃1的捕获组
- \\(-一个(字符
- (?:[^()]++|(?1))*-整个组1中除(和)之外（与[^()]++或（|）以外的1个以上字符的0个或更多字符模式（递归以匹配所有嵌套级别）
- \\)-一个)字符
(*SKIP)(*F)-这两个动词使引擎跳过当前匹配的字符串，并继续在此文本之后立即查找下一个匹配项。
|-或
,-逗号。

Answer 2

对this question的已接受答案进行编辑似乎就可以了。我只是在开始时添加了[[: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)"

正则表达式-用逗号分割字符串，在括号之间跳过任何内容

2 个答案: