Hi Jim,
 
I just wanted to know if there is a function in R that can tell you whether a file on the internet exists before you attempt to download it or whether there is a way of handling the error you get in the download.file() function without having it break a for loop with the download error when it is part of that loop.
Kind Regards
Chib



> Date: Mon, 31 Mar 2008 18:33:35 -0500> From: jholtman@gmail.com> To: chibco@hotmail.com> Subject: Re: [R] download.file error> CC: r-help@r-project.org> > ?try> > On Mon, Mar 31, 2008 at 6:26 PM, CHIB CO <chibco@hotmail.com> wrote:> > Dear all,> >> > I am looking for a way to work out if a file on the internet exists before attempting to download it using the function download.file(). For example,> > using a url that does not exist> >> > url <- "http://finance.yahoo.com/ftse.csv"> > destfile <- tempfile()> > download.file(url = url, destfile = destfile)> >> > # gives the following response ...> >> > trying URL 'http://finance.yahoo.com/ftse.csv'> > Error in download.file(url = url, destfile = destfile) :> > cannot open URL 'http://finance.yahoo.com/ftse.csv'> > In addition: Warning message:> > In download.file(url = url, destfile = destfile) :> > cannot open: HTTP status was '404 Not Found'> >> > When I am using the download.file() function in a loop over multiple URLs, the above error will cause the loop to terminate, so I want to avoid this by checking if the file exists first then wrapping the subsequent functions in an if() statment. The original fault came from the function get.hist.quote() in the "tseries" package. I was trying to iterate over various stocks, but some stocks listed in the yahoo website do not have any downloadable data associated with them, which causes the loop to terminate. The "workhorse" function of get.hist.quote() is the download.file() function.> >> > Kind Regards> >> > Chib> >> > _________________________________________________________________> > Win 100's of Virgin Experience days with BigSnapSearch.com> >> > [[alternative HTML version deleted]]> >> >> > ______________________________________________> > R-help@r-project.org mailing list> > https://stat.ethz.ch/mailman/listinfo/r-help> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code.> >> >> > > > -- > Jim Holtman> Cincinnati, OH> +1 513 646 9390> > What is the problem you are trying to solve?
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