R语言gsub替换字符工具的具体使用

2024-04-02 19:04:59 759人浏览八月长安

摘要

gsub()可以用于字段的删减、增补、替换和切割，可以处理一个字段也可以处理由字段组成的向量。具体的使用方法为：gsub("目标字符", "替换字符", 对象) 在gsub函数中，

gsub()可以用于字段的删减、增补、替换和切割，可以处理一个字段也可以处理由字段组成的向量。

具体的使用方法为：gsub("目标字符", "替换字符", 对象)

在gsub函数中，任何字段处理都由将“替换字符”替换到“目标字符”这一流程中实现，令替换字符为''''可实现删除，令替换字符为"目标字符+增补内容"可实现增补，替换和切割也是使用类似的操作。


> text <- "AbcdEfgh . Ijkl MNM"
> gsub("Efg", "AAA", text) #将Efg改为AAA，区分大小写
[1] "AbcdAAAh . Ijkl MNM"

任何符号，包括空格、Tab和换行都是可以识别的


> gsub(" I", "i", text)  #可识别空格
[1] "AbcdEfgh .ijkl MNM"

同时字符可以识别多个，进行批量置换


> gsub("M", "N", text) 
[1] "AbcdEfgh . Ijkl NNN"

除此之外，gsub还有其他批量操作的方法


> gsub("^.* ", "a", text) #开头直到最后一个空格结束替换成a
[1] "aMNM"
> gsub("^.* I(j).*$", "\\1", text) #只保留一个j
[1] "j"
> gsub(" .*$", "b", text) #第一个空格直达结尾替换成b
[1] "AbcdEfghb"
> gsub("\\.", "\\+", text) #句号.和加号+是特殊的，要添加\\来识别
[1] "AbcdEfgh + Ijkl MNM"

Syntax	Description
\\d	Digit, 0,1,2 ... 9
\\D	Not Digit
\\s	Space
\\S	Not Space
\\w	Word
\\W	Not Word
\\t	Tab
\\n	New line
^	Beginning of the string
$	End of the string
\	Escape special characters, e.g. \\ is "\", \+ is "+"
\|	Alternation match. e.g. /(e\|d)n/ matches "en" and "dn"
•	Any character, except \n or line terminator
[ab]	a or b
[^ab]	Any character except a and b
[0-9]	All Digit
[A-Z]	All uppercase A to Z letters
[a-z]	All lowercase a to z letters
[A-z]	All Uppercase and lowercase a to z letters
i+	i at least one time
i*	i zero or more times
i?	i zero or 1 time
i{n}	i occurs n times in sequence
i{n1,n2}	i occurs n1 - n2 times in sequence
i{n1,n2}?	non greedy match, see above example
i{n,}	i occures >= n times
[:alnum:]	Alphanumeric characters: [:alpha:] and [:digit:]
[:alpha:]	Alphabetic characters: [:lower:] and [:upper:]
[:blank:]	Blank characters: e.g. space, tab
[:cntrl:]	Control characters
[:digit:]	Digits: 0 1 2 3 4 5 6 7 8 9
[:graph:]	Graphical characters: [:alnum:] and [:punct:]
[:lower:]	Lower-case letters in the current locale
[:print:]	Printable characters: [:alnum:], [:punct:] and space
[:punct:]	Punctuation character: ! " # $ % & ' ( ) * + , - . / : ; < = > ? @ [ \ ] ^ _ ` { \| } ~
[:space:]	Space characters: tab, newline, vertical tab, fORM feed, carriage return, space
[:upper:]	Upper-case letters in the current locale
[:xdigit:]	Hexadecimal digits: 0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f