R语言中substr函数，字符串截取函数
1、测试1
x <- "dfserut" x substr(x,1,3) substr(x,2,5) substr(x,2) substring(x,2)
2、测试2
x <- c("sfwsfs","ydsfs","gdsge","mhxsf") x substr(x,1,3) substring(x,3)
应用于向量
3、测试3
v1 <- c("sfde","fsdf","rere") v2 <- c("erea","rftg","cfsd") x <- data.frame(v1,v2) x substr(x$v1,1,2) substring(x$v1,3)
应用于数据框
4、测试4
x <- "dfserut" x substr(x,1,3) substr(x,1,3) <- "ABC" x substr(x,1,3) <- "M" x
