R/Linkparamsfilter.R

In Rcrawler: Web Crawler and Scraper

#' Link parameters filter
#'
#' This function remove a given set of parameters from a specific URL
#' @param URL character, the URL from which params and values have to be removed
#' @param params character vector, List of url parameters to be removed
#' @param removeAllparams, boolean if true , all url parameters will be removed.
#' @return return a URL wihtout given parameters
#' @author salim khalil
#' @details
#' This function exclude given parameters from the urls,
#' @export
#' @examples
#' #remove ord and tmp parameters from the URL
#' url<-"http://www.glogile.com/index.php?name=jake&age=23&tmp=2&ord=1"
#' url<-Linkparamsfilter(url,c("ord","tmp"))
#' #remove all URL parameters
#' Linkparamsfilter(url,removeAllparams = TRUE)
#'
Linkparamsfilter<-function(URL, params, removeAllparams=FALSE){
  if(missing(URL)) stop ("You need to provide URL argument")
  if(!missing(params) && removeAllparams) warning ("params argument is omitted because remove all remove all parameter")
  if(missing(params) && !removeAllparams) stop("you should specify parameters to be deleted ")
  str<-URL
  if(!removeAllparams){
  paramsv<-Linkparameters(str)
  if (!is.null(paramsv)){
      #extract parameters names
      paramsid<-unlist(lapply(paramsv, FUN = function(el) gsub("(.*)\\=.*", "\\1", el)))
      nbparams<-length(paramsid)
      for (i in 1:length(params)){
      #if the parameter exist in the url
          if(params[i] %chin% paramsid) {
            paramsv<-Linkparameters(str)
            nbparams<-length(unlist(lapply(paramsv, FUN = function(el) gsub("(.*)\\=.*", "\\1", el))))
            if (nbparams>1) {
                paramsi<-grep(paste("^",params[i],"$", sep = ""), paramsid)
                if(paramsi>1){
                  pat<-paste("&",paramsv[paramsi],sep="")
                  str<-gsub(pat,'',str)
                } else {
                  pat<-paste(paramsv[paramsi],"&",sep="")
                  str<-gsub(pat,'',str)
                }
            } else {
              paramsi<-grep(paste("^",params[i],"$", sep = ""), paramsid)
              pat<-paste("\\?",paramsv[paramsi],sep="")
              str<-gsub(pat,'',str)
            }
          }
      }
  } else str<-URL
  } else {
    str<-gsub("\\?(.*)","",str)
  }
  return (str)
}