R/extxt.R

In nbarsch/tfwstring:

#' extxt()
#' extract parts from a string based on defined string split
#' @param string string to split on to find what to extract
#' @param ps page source in text unlisted to find what to extract 
#' @param nchar number of characters from located string forward to extract
#' @param firstonly if TRUE returns only first instance of extract
#' @export
extxt <- function(string,ps,nchar=100,firstonly=F){
  startchar <- str_locate_all(ps,string)[[1]]
  if(length(startchar)>0){
    
    if(!isTRUE(firstonly)){
      sapply(c(1:nrow(startchar)),FUN=function(x){
        if(isTRUE((startchar[x]+nchar)<nchar(ps))){
          return(substr(ps,startchar[x],startchar[x]+nchar))
        }else{
          return(substr(ps,startchar[x],nchar(ps)))
          #substr(ps,startchar[x],nchar(startchar[x]))
          
        }
      })
    }else{
      if(isTRUE((startchar[1]+nchar)<nchar(ps))){
        return(substr(ps,startchar[1],startchar[1]+nchar))
      }else{
        return(substr(ps,startchar[1],nchar(ps)))
      }
    }
  }else{
    return("NOT_FOUND")
  }
}