R help - Jan 2004 - write.table file="file.txt" help

Hi all,

I have a R script that creates several input files for an analysis 
program.  It loops through the matrix read into R and picks out 
submatrices and then creates a separate output file for each 
submatrix.  The loop works great, but I am having trouble getting all 
the separate output files written.

The line I have is:

write.table(ch1d, file="C:/WINDOWS/Desktop/SNPs/haplo.txt", 
row.names=F, col.names=F, append=F, quote=F)

Which works just fine if I just wanted to create a single file from the 
loop.  However, I need to somehow get it to change the name of the 
output file ("haplo.txt") each time it goes through the loop so it 
doesn't overwrite each time.  In perl, I'd create $n=1 and increment up 
each loop, and call the file something like "haplo.txt.$n"  

I tried to do something like that but R doesn't recognize the variable 
that would be $n in perl (because it's part of the quoted name of the 
output file).  Adding it after the ending " just gave me an error, as I 
thought it would.

I also tried to use system(copy ...) to change the name of the file in 
dos, but my knowledge of dos is abysmal, so I was unable to do it.

Any ideas on how to go about doing this would be most appreciated!

Thanks in advance,
KK Nicodemus

Look at ?paste

for (j in 1:10) { 
   write.table(j, file=paste("haplo.txt", j, sep="."), 
               row.names=F, col.names=F, append=F, quote=F)
}

BTW, there have been many similar posts like this in the past. They are
easily found using the search function at 
http://cran.r-project.org/search.html 

HTH, Andy

Kristin Kay Nicodemus wrote:
> Hi all,
> 
> I have a R script that creates several input files for an analysis 
> program.  It loops through the matrix read into R and picks out 
> submatrices and then creates a separate output file for each 
> submatrix.  The loop works great, but I am having trouble getting all 
> the separate output files written.
> 
> The line I have is:
> 
> write.table(ch1d, file="C:/WINDOWS/Desktop/SNPs/haplo.txt", 
> row.names=F, col.names=F, append=F, quote=F)
> 
> Which works just fine if I just wanted to create a single file from the 
> loop.  However, I need to somehow get it to change the name of the 
> output file ("haplo.txt") each time it goes through the loop so
it
> doesn't overwrite each time.  In perl, I'd create $n=1 and
increment up
> each loop, and call the file something like "haplo.txt.$n"  
> 
> I tried to do something like that but R doesn't recognize the variable 
> that would be $n in perl (because it's part of the quoted name of the 
> output file).  Adding it after the ending " just gave me an error, as
I
> thought it would.
> 
> I also tried to use system(copy ...) to change the name of the file in 
> dos, but my knowledge of dos is abysmal, so I was unable to do it.
> 
> Any ideas on how to go about doing this would be most appreciated!
> 
> Thanks in advance,
> KK Nicodemus
> 
Use paste().

for(i in 1:n) {
   file <- paste("C:/WINDOWS/Desktop/SNPs/haplo", i,
"txt", sep = ".")
   cat("Writing data to", file, "\n")
   write.table(ch1d, file=file,
             row.names=F, col.names=F, append=F, quote=F)
}

-sundar

Thanks to Andy Bunn and Patrick Connolly for their help!

Kristin Nicodemus