认真聊一聊R语言中的paste/paste0函数

作者：白介素2

聊一聊引无数英雄竞折腰的 paste函数

来，我们将将镜头推进，仔细的研究一下paste函数

paste函数可用于字符串连接

?paste# 看看文档大概了解下
## starting httpd help server ... done

我们简单举个例子

paste("a","b") #能连接a b
## [1] "a b"
paste("a","b","c")
## [1] "a b c"
#设置分隔符
paste("a","b",sep = "=")##注意到用等号分隔了
## [1] "a=b"
#连接多个元素
paste("a",1:5,sep = "")#会自动每个元素与a相连
## [1] "a1" "a2" "a3" "a4" "a5"
paste("a",1:5,".pdf", sep = "")#比如想批量输出文件名
## [1] "a1.pdf" "a2.pdf" "a3.pdf" "a4.pdf" "a5.pdf"

collapse参数，谢益辉大佬说这个参数引无数英雄竞折腰啊，大家只会sep

paste("a",1,collapse = "+")##注意到了吧，collapse没用上
## [1] "a 1"
paste(c("a","b","c"),collapse = "+") #这样就很容易理解了，collapse折叠起了元素
## [1] "a+b+c"
# 再来更明显的举例
paste("a",1:5,sep = "")##先在元素间连接
## [1] "a1" "a2" "a3" "a4" "a5"
#然后折叠
paste("a",1:5,sep = "",collapse = "+")
## [1] "a1+a2+a3+a4+a5"

这样总结一下，sep连接的是元素间的扩展，collapse是一种元素间的折叠坍缩

与paste0函数的区别

paste0函数，默认sep=""是两个函数唯一的区别

paste(c("a", "b","c"),1:3)##默认空格符
## [1] "a 1" "b 2" "c 3"
paste(c("a", "b","c"),1:3,sep=" ")
## [1] "a 1" "b 2" "c 3"
paste(c("a", "b","c"),1:3,sep="")
## [1] "a1" "b2" "c3"
#如果两个向量长度不同
paste(c("a", "b","c"),1:5)##超出范围后继续从前向后连接
## [1] "a 1" "b 2" "c 3" "a 4" "b 5"
#paste0的表现
paste0(c("a", "b","c"),1:3)#默认元素连接为sep=""
## [1] "a1" "b2" "c3"