Re: [R] readJPEG function cannot open jpeg files

[Prof Brian Ripley]

On 14/01/2013 16:26, Suzen, Mehmet wrote:
Similar issue with URLs:

Not a similar issue at all: a URL is not a file.  That most functions in 
R itself open connections including URLs does not mean that contributed 
packages do.  The package help is quite specific about its requirements.

  source: Either name of the file to read from or a raw vector
          representing the JPEG file content.

Which suggests to you how you can do this, apart from download.file, of 
course.  Something like

readJPEG(readBin(yesWeCan, "raw", 1e6))


yesWeCan <- 
"http://upload.wikimedia.org/wikipedia/commons/9/9d/Barack_Obama.jpg";
url(yesWeCan)
                                                           description
"http://upload.wikimedia.org/wikipedia/commons/9/9d/Barack_Obama.jpg";
                                                                 class
                                                                 "url"
                                                                  mode
                                                                   "r"
                                                                  text
                                                                "text"
                                                                opened
                                                              "closed"
                                                              can read
                                                                 "yes"
                                                             can write
                                                                  "no"
readJPEG(yesWeCan)
Error in readJPEG(yesWeCan) :
   unable to open
http://upload.wikimedia.org/wikipedia/commons/9/9d/Barack_Obama.jpg


On 14 January 2013 14:57, Yi Yuan <lamban...@gmail.com> wrote:
I installed jpeg package and tried to use

  kim<-readJPEG("kim.jpeg") to read in a jpeg file, but R gave me an error:
Error in readJPEG("kim.jpeg") : unable to open kim.jpeg

I already put "kim.jpeg" in Rstudio's default working directory: "E:\home
work\Rstudio". So I don't think it's a problem caused by omitting the file's
path. But I tried with the full path version just in case and still got the
"unable to open" error:

kim<-readJPEG("E:\\ home work\\Rstudio\\kim.jpeg")
Error in readJPEG("E:\\ home work\\Rstudio\\kim.jpeg") :
   unable to open E:\ home work\Rstudio\kim.jpeg

So now I really don't know what is wrong.

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--
Brian D. Ripley,                  rip...@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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