A Cheat Sheet of Common Regex Task Chunks

Usage

cheat(dictionary = qdapRegex::regex_cheat, print = TRUE)

Arguments

dictionary

A dictionary of cheat terms. Default is regex_cheat.

print

logical. If TRUE the left justified output is printed to the console.

Examples

cheat()

   NAME                REGEX    WHAT IT DOES                                       
1  Lookahead           (?=foo)  What follows is `foo`                              
2  Lookbehind          (?<=foo) What precedes is `foo`                             
3  Negative Lookahead  (?!foo)  What follows is not `foo`                          
4  Negative Lookbehind (?<!foo) What precedes is not `foo`                         
5  Non-Capturing Group (?:foo)  Match this group (`foo`) but with no capture       
6  Exception           [^X]     Match everything except `X`                        
7  Dot                 .        Match any character                                
8  Case Insensitive    (?i:foo) Matches irregardless of case; `Foo` & `foO` matched
9  Digit               \\d      Match digits (i.e., [0-9])                         
10 Non-Digit           \\D      Match non-digits (i.e., [^0-9])                    
11 Word                \\w      Match words (i.e., [_a-zA-Z0-9])                   
12 Non-Word            \\W      Match non-words (i.e., [^_a-zA-Z0-9])              
13 Whitespace          \\s      Match whitespace (i.e., [ \\t\\r\\n\\f])           
14 Non-Whitespace      \\S      Match non-whitespace (i.e., [^ \\t\\r\\n\\f])      
15 Word Boundary       \\b      Match beginning/end of word                        
16 Non-Word Boundary   \\B      Match not beginning/end of word                    
17 0-1 (Greedy)        x?       Match 0-1 times greedy                             
18 0-1 (Lazy)          x??      Match 0-1 times lazy                               
19 >= 0 (Greedy)       x*       Match 0 or more times greedy                       
20 >= 0 (Lazy)         x*?      Match 0 or more times lazy                         
21 >= 1 (Greedy)       x+       Match 1 or more times greedy                       
22 >= 1 (Lazy)         x+?      Match 1 or more times lazy                         
23 Exactly N           x{4}     Match N times                                      
24 Min-Max             x{4,8}   Match min-max times                                
25 > N                 x{9,}    Match N or more times                              

See also