Dear all, I want to let R automatically download available files from a website in certain folders. Since the files I need, if exist, are in a certain directory, I used download.file() function with a predesigned directory. However, some of the folders do not have the file I want. When this occurs, my program returns error and terminates. So I wonder if there is any way that I can check if a directory exists before downloading that file. I appreciate your help! Thanks! Wendy [[alternative HTML version deleted]]
On 26/04/11 05:52, Wendy Han wrote:> Dear all, > > > > I want to let R automatically download available files from a website in > certain folders. Since the files I need, if exist, are in a certain > directory, I used download.file() function with a predesigned directory. > However, some of the folders do not have the file I want. When this occurs, > my program returns error and terminates. So I wonder if there is any way > that I can check if a directory exists before downloading that file. I > appreciate your help!Not quite sure I understand your question, but I think that the file.info() function will provide what you need. Check out ?file.info. See also ?files and ?file.access. cheers, Rolf Turner
On Mon, 2011-04-25 at 12:52 -0500, Wendy Han wrote:> I want to let R automatically download available files from a website in > certain folders. Since the files I need, if exist, are in a certain > directory, I used download.file() function with a predesigned directory. > However, some of the folders do not have the file I want. When this occurs, > my program returns error and terminates. So I wonder if there is any way > that I can check if a directory exists before downloading that file. I > appreciate your help!You could use the try() command to catch the download.file() error and, if there is one, handle it accordingly. See help(try) Regards, Jerome
Use try() or tryCatch() to let your loop continue looking for more files after download.file() throws an error. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com> -----Original Message----- > From: r-help-bounces at r-project.org > [mailto:r-help-bounces at r-project.org] On Behalf Of Rolf Turner > Sent: Monday, April 25, 2011 3:30 PM > To: Wendy Han > Cc: r-help at r-project.org > Subject: Re: [R] About How to check if a html directory exists > > On 26/04/11 05:52, Wendy Han wrote: > > Dear all, > > > > > > > > I want to let R automatically download available files from > a website in > > certain folders. Since the files I need, if exist, are in a certain > > directory, I used download.file() function with a > predesigned directory. > > However, some of the folders do not have the file I want. > When this occurs, > > my program returns error and terminates. So I wonder if > there is any way > > that I can check if a directory exists before downloading > that file. I > > appreciate your help! > > Not quite sure I understand your question, but I think that the > file.info() function will provide what you need. Check out > ?file.info. > See also ?files and ?file.access. > > cheers, > > Rolf Turner > > ______________________________________________ > R-help at 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. >