Colleagues,

Several days ago, I queried about using the "system" command to open a  
PDF file.  A number of people responded, each providing useful ideas.   
I integrated these ideas into a function that others can tailor to  
their needs:

OPENPDF         <- function(PDFFILENAME)
         {
         OPENPDFCOMMAND  <- "open"       		# applies to OS X
         if (!UNIX)      OPENPDFCOMMAND  <- "start"	# applies to Windows
         if (LINUX)
                 {
                 OPENPDFCOMMAND          <- getOption("pdfviewer")	# S- 
Plus does not set this option
									# also, R appears to not set it in SUSE
                 TESTTHESE               <- c("xpdf", "evince",  
"acroread")
                 if (is.null(OPENPDFCOMMAND))				# look for  
application named ...
                         {
                         for (EachTest in TESTTHESE)
                                 {
                                 VALUE                   <-  
SYSTEM(paste("locate", EachTest))
                                 if (length(VALUE) > 0)   
{ OPENPDFCOMMAND        <- VALUE }
                                 }
                         }
                 }
         if (!is.null(OPENPDFCOMMAND) & file.exists(PDFFILENAME))
                 { SYSTEM(paste(OPENPDFCOMMAND, PDFFILENAME)) } else  
invisible()
         }

This version calls other functions that I have written, e.g., UNIX and  
LINUX, each of which identifies the OS.  The SYSTEM command is  
specific for the OS (e.g., system in OS X and Linux, shell in Windows;  
intern=T in all cases).

If anyone has suggestions for improvement, I would be delighted to  
receive them.

Dennis


Dennis Fisher MD
P < (The "P Less Than" Company)
Phone: 1-866-PLessThan (1-866-753-7784)
Fax: 1-415-564-2220
www.PLessThan.com


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