R help - Jun 2005 - reading non-existing files

Dear all,

I'm trying to read to a collection of files in a loop
using odbcConnectExcel - but not all of the files
exist. This is the code I have

for(i in 1:no.of.subs){
   channel <- odbcConnectExcel(paste(working.dir,
subs[i], ".xls", sep=""))
   datafiles[[i]] <- as.matrix(sqlFetch(channel,
"Data"))          
   close(channel)
}

I'm not sure how to alter the code to allow for the
fact that some files may not exist - these files
should be ignored.

Currently, I get the following error

Error in odbcTableExists(channel, sqtable) : 
        'Data': table not found on channel

- it however creates an empty file for the first
occurance of a non-existing file then stops.

I would very much apprepriate any help.

Thanks in advance.

Dave



		
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file.exists():
if(!file.exists(your.file)) next

Or, try():
your.data <- try(as.matrix(whatever))
if (class(your.data) == "try-error") {something went wrong / the file
doesn't exist - just for logging, the code will not fail}



-----Original Message-----
From: Dave Evens [mailto:devens8765 at yahoo.com]
Sent: Tuesday, June 07, 2005 12:48 PM
To: r-help at stat.math.ethz.ch
Subject: [R] reading non-existing files



Dear all,

I'm trying to read to a collection of files in a loop
using odbcConnectExcel - but not all of the files
exist. This is the code I have

for(i in 1:no.of.subs){
   channel <- odbcConnectExcel(paste(working.dir,
subs[i], ".xls", sep=""))
   datafiles[[i]] <- as.matrix(sqlFetch(channel,
"Data"))          
   close(channel)
}

I'm not sure how to alter the code to allow for the
fact that some files may not exist - these files
should be ignored.

Currently, I get the following error

Error in odbcTableExists(channel, sqtable) : 
        'Data': table not found on channel

- it however creates an empty file for the first
occurance of a non-existing file then stops.

I would very much apprepriate any help.

Thanks in advance.

Dave



		
__________________________________ 

Get on-the-go sports scores, stock quotes, news and more. Check it out!

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On Tue, 07-Jun-2005 at 09:48AM -0700, Dave Evens wrote:

|> 
|> Dear all,
|> 
|> I'm trying to read to a collection of files in a loop
|> using odbcConnectExcel - but not all of the files
|> exist. This is the code I have

Try try().

Use a condition on what you get back to avoid attempting to do things
to empty files.

?try will be a good place to start.

-- 
Patrick Connolly
HortResearch
Mt Albert
Auckland
New Zealand 
Ph: +64-9 815 4200 x 7188
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