When we want to call external programs in R under Windows, we often need to know the paths of these programs. For instance, we may want to know where ImageMagick is installed, as we need the convert (convert.exe) utility to convert images to other formats, or where OpenBUGS is installed because we need this path to use the function bugs(). Usually this problem does not exist under Linux, because the executables (or their symbolic links) are often put in the directories which are in the environment variable PATH (e.g. /usr/bin, /usr/local/bin).
However, we may be able to find the paths through the registry if the installation will save the path info in the registry hive. The R function is readRegistry():
## ImageMagick:
## I used this trick in the function saveMovie (the animation package)
> readRegistry("SOFTWARE\\ImageMagick\\Current")
$BinPath
[1] "C:\\Program Files\\ImageMagick"
$CoderModulesPath
[1] "C:\\Program Files\\ImageMagick\\modules\\coders"
$ConfigurePath
[1] "C:\\Program Files\\ImageMagick\\config"
$FilterModulesPath
[1] "C:\\Program Files\\ImageMagick\\modules\\filters"
$LibPath
[1] "C:\\Program Files\\ImageMagick"
$QuantumDepth
[1] 16
$Version
[1] "6.3.8"
## OpenBUGS
> r = names(readRegistry("Software\\Microsoft\\Windows\\ShellNoRoam\\MUICache",
+ "HCU"))
> dirname(r[grep("OpenBUGS\\.exe", r)])
[1] "C:/Program Files/OpenBUGS"
There is no guarantee for this approach to work on any Windows platforms, but I think this is better than explaining what is the PATH variable to some Windows users…
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