Thursday, 22 March 2012

Check URL existance with R

RCurl package provides utilities for HTTP and FTP connection. One particular functionality is checking if a given URL is accessible, implying existence, using url.exists. However some unfortunate Windows users may have difficulty to get its latest build from CRAN. Here is a simple function to check existence of URL by only using R base functionality;
   urlExists <- function(address) {  
     tryCatch {  
      con <- url(address)  
      a  <- capture.output(suppressWarnings(readLines(con)))  
      close(con)  
      TRUE;  
     },  
       error = function(err) {  
       occur <- grep("cannot open the connection", capture.output(err));  
       if(length(occur) > 0) FALSE;  
      }  
    )  
   }  

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(c) Copyright 2008-2017 Mehmet Suzen (suzen at acm dot org)

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