R语言笔记

## 1 Rstudio快捷键 > Alt + - 快捷输入 <-

2 R中字符串操作

字符串链接 paste( )

1	paste(..., sep = " ", collapse = NULL)

用法： ... 为字符； sep=" " 中的 " " 为分隔符； collaspse= NULL表示连成一个字符串，如果将NULL修改成 "," 则将字符连接成一个字符，并用，分隔。
例：

> paste("A","B")
[1] "A B"

> paste("A","B",sep=",")
[1] "A,B"

> paste("A",1:3,sep="")
[1] "A1" "A2" "A3"

> paste("A", 1:3 ,sep = "" ,collapse = ",")
[1] "A1,A2,A3"

### 字符串替换 gsub( )

1 2	gsub(pattern, replacement, x, ignore.case = FALSE, perl = FALSE, fixed = FALSE, useBytes = FALSE)

用法： pattern 为需要替换的字符；replacement为替换后的字符；x为包含字符的向量。例：

> a <- "abc,d"
> a
[1] "abc,d"

> b <- gsub("a","x",a)
> b
[1] "xbc,d"

> b <- gsub(",", "x", a, fixed = TRUE)
> b
[1] "abcxd"

## 3 批量赋值 assign( )

1 2	assign(x, value, pos = -1, envir = as.environment(pos), inherits = FALSE, immediate = TRUE)

用法：将value 的值赋给x 例：

> value <-  c(1:3)
> x <- c("a","b","c")
> > for (i in x) {
+     assign(i,value)
+ }
>a
[1] 1 2 3
>b
[1] 1 2 3
>c
[1] 1 2 3