R语言字符串函数

字符串长度：

nchar("hello world")

#字符串连接：
paste() #paste(..., sep = " ", collapse = NULL)

#字符串分割：
strsplit() #strsplit(x, split, extended = TRUE, fixed = FALSE, perl = FALSE)

#计算字符串的字符数：
nchar()

#字符串截取：
substr(x, start, stop)
substring(text, first, last = 1000000)
substr(x, start, stop) <- value
substring(text, first, last = 1000000) <- value

substr("abcdef", 2, 4)
[1] "bcd"

> x <- "1234567890"
> substr(x, 3, 3)
[1] "3"
>
> substr(x, 5, 7)
[1] "567"
>
> substr(x, 4, 4) <- "A"
> x
[1] "123A567890"
>
> substr(x, 2, 4) <- "TTF"
> x
[1] "1TTF567890"
>
> substr(x, 9, 12) <- "ABCD"
> x
[1] "1TTF5678AB"
>
> substring(x, 5)
[1] "5678AB"
>
> substring(x, 5) <- "..."
> x
[1] "1TTF...8AB"

#字符串替换及大小写转换：
chartr(old, new, x)
tolower(x)
toupper(x)
casefold(x, upper = FALSE)

x=gsub(old_strin, new_string, x) # replace string 字符串替换

grepl(value, chars)

# chars contains value? (TRUE, FALSE)

#字符串比较：

if(as.character(x)==as.character(y))