我们可以在stringi包中使用stri_sub函数。
> x<- "nhooo is the largest online library for best tutorials" > x [1] "nhooo is the largest online library for best tutorials" > library(stringi) > stri_sub(x,1,9) [1] "Tutorials" > stri_sub(x,1,-20) [1] "nhooo is the largest online library" > stri_sub(x,-14,-1) [1] "best tutorials" > stri_sub(x,-41,-1) [1] "largest online library for best tutorials"