R字符串處理

R 字符串處理

1 #字符串連接：
paste() #paste(..., sep = " ", collapse = NULL)
> paste("a","b","c",sep=">")
[1] "a>b>c"
2 字符串分割：
strsplit() #strsplit(x, split, extended = TRUE, fixed = FALSE, perl = FALSE)
> strsplit("a>b>c",">")
[[1]]
[1] "a" "b" "c"
3 #計算字符串的字符數：
nchar()
> nchar("a>b>c")
[1] 5
4 #字符串截取：
substr(x, start, stop)
> paste("a","b","c",sep=">")->mm
> substr(mm, 1, 3)
[1] "a>b"
substring(text, first, last = 1000000L)
> substring(mm, 1, 3)
[1] "a>b"
> substring(mm,1,1:3)
[1] "a"   "a>"  "a>b"
解釋
1代表從第一個字母開始
1:3代表取(1,1),(1,2),(1,3)
substr(x, start, stop) <- value
以下是進行字符串的替換
substring(text, first, last = 1000000) <- value
#字符串替換及大小寫轉換：
chartr(old, new, x)
> chartr("a","dd",mm)
[1] "d>b>c"
注:只能替換相同的字符數
toupper(x)
> toupper(mm)
[1] "A>B>C"
tolower(x)
> tolower(mm)
[1] "a>b>c"
casefold(x, upper = TRUE)
> casefold(mm, upper = TRUE)
[1] "A>B>C"
紅色的起着重要作用.FALSE的話就還是和以前一樣了