Using jpeg (file =) creates an empty jpeg even if there is no call to generate the graph
This is observed in the party. Considering the following code snippet, I don't understand why R creates an empty jpeg file on Windows, even though I am not naming a graph or graph. When I run similar code under Linux or OS X, no jpeg file is generated. I don't know in advance if the user wants to plot, so I set the filename in advance and give them a name and location.
##
sink("c:\\temp\\test.lst")
jpeg(file="c:\\temp\\test%d.jpeg")
norm <- rnorm(100)
print(norm)
Any suggestions would be appreciated.
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The help file ?jpeg
(which also applies to devices bmp()
, png()
and tiff()
) indicates that:
The ‘type = "windows"’ versions of these devices effectively plot
on a hidden screen and then copy the image to the required format.
This Windows-specific implementation detail most likely explains the difference in behavior between Windows and * NIX systems.
On Windows, calling any of the above functions (and pdf()
and postscript()
) creates a file --- regardless of whether you draw anything on that hidden screen. Except for pdf()
(which creates files that I cannot open with the viewer), the image registered to the build device is a white rectangle of height and width specified when the specific device is called.
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I wouldn't bother with that. if the prospect of zero-length files cluttering a folder bothers you, you can clean up after which something like
jpgs <- file.path("c:/temp", dir(pattern="c:/temp/test[0-9]*\\.jpeg"))
s <- file.info(jpgs)[["size"]]
for(i in seq_along(s))
if(s[i] == 0) file.remove(jpgs[i])
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