R语言拼接字符串_paste的用法说明

paste (…, sep = " ", collapse = NULL)

paste("Hello", "xiaoming", sep = "-")

paste("Hello", 1:2, sep = "-")

paste("Hello", 1:2, sep = "-", collapse = ",")

fruit <- 'apple orange grape banana'
nchar(fruit)
length(fruit)   #元素个数为1
[1] 1

> strsplit(fruit,split=' ')
[[1]]
[1] "apple"  "orange" "grape"  "banana"    #list结构
> fruitvec <- unlist(strsplit(fruit,split=' '))
> fruitvec
[1] "apple"  "orange" "grape"  "banana"   #转化为向量

paste(fruitvec,collapse=',')    #逗号作为分隔符
[1] "apple,orange,grape,banana"

substr(fruit, 1,5)
[1] "apple"

> chartr('world','bear',a)   #字母替换
Error in chartr("world", "bear", a) : 'old' is longer than 'new' #字符长度要求一致
> chartr('world','beara',a)
[1] "herre beara"
> x<-'i love you'
> chartr('you','she',x)   #实际是字母替换，不是字符串替换
[1] "i lhve she"
> a<-'i love you, do you love me ?'
> sub('you','she', a)            #只替换第一个参数you
[1] "i love she, do you love me ?"
> gsub('you','she', a)           #可以替换全部参数 
[1] "i love she, do she love me ?"  
gsub('apple','strawberry',fruit)
[1] "strawberry orange grape banana"

grep('grape',fruitvec)   #返回grape在fruitvec中的位置
[1] 3 

> a <- "Hello World"
> toupper(a)    #全部替换为大写
[1] "HELLO WORLD"
> tolower(a)    #全部替换为小写
[1] "hello world"