break string at specified possitions

Hi Jan,
This might be helpful:

chop_string<-function(x,ends) {
 starts<-c(1,ends[-length(ends)]-1)
 return(substring(x,starts,ends))
}

Jim


On Thu, May 12, 2016 at 7:23 AM, Jan Kacaba <jan.kacaba at gmail.com> wrote:

Here is my attempt at function which computes margins from positions.

require("stringr")
require("dplyr")

ends<-seq(10,100,8)  # end margins
test_string<-"Lorem ipsum dolor sit amet, consectetuer adipiscing
elit. Aliquam in lorem sit amet leo accumsan lacinia."

sekoj=function(ends){
  l_ends<-length(ends)
  begs=vector(mode="integer",l_ends)
  begs[1]=1
  for (i in 2:(l_ends)){
    begs[i]<-ends[i-1]+1
  }
  margs<-rbind(begs,ends)
  margs<-cbind(margs,c(ends[l_ends]+1,-1))
  #rownames(margs)<-c("beg","end")
  return(margs)
}
margins<-sekoj(ends)
str_sub(test_string,margins[1,],margins[2,]) %>% print

Code to run in browser:
http://www.r-fiddle.org/#/fiddle?id=rVmNVxDV

2016-05-11 23:12 GMT+02:00 Bert Gunter <bgunter.4567 at gmail.com>:

Dunno -- but you might have a look at Hadley Wickham's 'stringr' package:
https://cran.r-project.org/web/packages/stringr/stringr.pdf

Cheers,

Bert


Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Wed, May 11, 2016 at 1:12 PM, Jan Kacaba <jan.kacaba at gmail.com> wrote:

Dear R-help

I would like to split long string at specified precomputed positions.
'substring' needs beginings and ends. Is there a native function which
accepts positions so I don't have to count second argument?

For example I have vector of possitions pos<-c(5,10,19). Substring
needs input first=c(1,6,11) and last=c(5,10,19). There is no problem
to write my own function. Just asking.

Derek