r语言 - 如何列出regex字符类的成员，如[:punct:]

Question

例如，我从诸如

之类的文档中知道

http://stat.ethz.ch/R-manual/R-devel/library/base/html/regex.html

[:punct:]

包括

! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [  ] ^ _ ` { | } ~.

，但我想从命令行检查(在我的情况下，R，但可能类似于bash等)，并列出[:alpha:]等

Answer 1

 grep("[[:punct:]]", unlist(strsplit(rawToChar(as.raw(1:127)), "")), value = TRUE)
 ## [1] "!"  """ "#"  "$"  "%"  "&"  "'"  "("  ")"  "*"  "+"  ","  "-"  "."  "/" 
 ## [16] ":"  ";"  "<"  "="  ">"  "?"  "@"  "["  "\" "]"  "^"  "_"  "`"  "{"  "|" 
 ## [31] "}"  "~" 
gsub("[^[:punct:]]", "", rawToChar(as.raw(1:127)), "")
## [1] "!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~"

Answer 2

如果您只需要担心ASCII，那么可以使用下面的代码(使用bash):

$ for n in {0..127}; do awk '{ printf("%c", $0); }' <<< $n | grep '[[:punct:]]' | tr 'n' ' '; done
! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [  ] ^ _ ` { | } ~
$ for n in {0..127}; do awk '{ printf("%c", $0); }' <<< $n | grep '[[:alnum:]]' | tr 'n' ' '; done
0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z a b c d e f g h i j k l m n o p q r s t u v w x y z