Duffau Duffau - 2 years ago 383
Bash Question

Error running ImageMagick from R: Invalid parameter

I am trying to make a GIF-animation in R. I have an array of matrices which i wish to convert into a GIF animation. My strategy is inspired from this example:


where the following code produces 11 PNG-Pictures with the "png"-function in R. Next it calls for the external ImageMagick-program "convert" to compile the GIF animation.


# Animated countdown from 10 to "GO!".
png(file="example%02d.png", width=200, height=200)
for (i in c(10:1, "G0!")){
text(.5, .5, i, cex = 6)

# convert the .png files to one .gif file using ImageMagick.
system("convert -delay 80 *.png example_1.gif")
#shell("convert -delay 80 *.png example_1.gif")

The problem is that R doesn't seem to finde the exe-file "convert" which is a part of ImageMagick and installed on the C-drive (C:\Program Files\ImageMagick-6.8.5-Q16). In the comments to the website i am linking to earlier, it is suggested for Windows users to use "shell" instead of "system" to run external programs but none of the two work. The error message is

Invalid parameter - 80
Warning message:
running command 'convert -delay 80 *.png example_1.gif' had status 4

I've tried to change the Windows PATH enviroment variable in the systems properties, as suggested in this answer, but the PATH-variable was allready corectlly defined on my system. I also tried specifying the whole string of the convert.exe file, but also without luck...

How can i get ImageMagick to run through R?

Windows 7 Servicepack 1,
R 3.0.0

Thanks in advance...

Answer Source

On Windows, there are several convert.exe commands, all of which are in the PATH. So you must specify the path to the right convert.exe executable. In my case, I had it in the LyX folder (however, you will find it in the ImageMagick installation too). Be careful with the quotes, the backslashes and the spacing if you are pasting. E.g. from within R:

system('"C:\\Program Files (x86)\\LyX 2.0\\imagemagick\\convert.exe" -delay 20 -loop 0 files_*.png animation.gif')
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