[R] readJPEG function cannot open jpeg files

William Dunlap wdunlap at tibco.com
Mon Jan 14 17:44:18 CET 2013

You can use file.info("myFile") to make sure the file exists and has appropriate permissions ("mode"
in file.info's lingo, as in Unix).  E.g.,

> file.info("c:/temp/BO.jpeg") # this one does not exist
                size isdir mode mtime ctime atime  exe
c:/temp/BO.jpeg   NA    NA <NA>  <NA>  <NA>  <NA> <NA>
> file.info("c:/temp/BO.jpg") # this one exists
                 size isdir mode               mtime               ctime               atime
c:/temp/BO.jpg 150536 FALSE  666 2013-01-14 08:35:32 2013-01-14 08:33:09 2013-01-14 08:33:09
c:/temp/BO.jpg  no

I can readJPEG() the file with mode 666, but not all permission information is encoded in the mode. 

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 Jeff Newmiller
> Sent: Monday, January 14, 2013 8:25 AM
> To: Yi Yuan; r-help at r-project.org
> Subject: Re: [R] readJPEG function cannot open jpeg files
> Being unable to open a file is a related to your operating system and how R interacts with
> that OS. If your interactive development environment (IDE, of which RStudio is an
> example) is trying to make things simpler for you but you don't understand how to use it,
> then you need to ask help from your RStudio support resources, not here.
> When posting here, you should mention your results from using base R functions like
> ?sessionInfo
> ?getwd
> ?list.files
> as indicated in the Posting Guide mentioned at the bottom of every R-help email.
> Consistent with the fact that this is an interface issue between R and the OS, sometimes
> you will have to investigate the problem from outside R. For example, you might need to
> investigate issues with security permissions that are OS specific and completely outside
> the scope of this forum.
> ---------------------------------------------------------------------------
> Jeff Newmiller                        The     .....       .....  Go Live...
> DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live Go...
>                                       Live:   OO#.. Dead: OO#..  Playing
> Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
> /Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
> ---------------------------------------------------------------------------
> Sent from my phone. Please excuse my brevity.
> Yi Yuan <lambandme at 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.
> >
> >	[[alternative HTML version deleted]]
> >
> >______________________________________________
> >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.
> ______________________________________________
> 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.

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