On Jan 6, 2012, at 12:43 PM, Mary Kindall wrote:
I have two one dimensional list of elements and want to perform
cbind and
then write into a file. The number of entries are more than a
million in
both lists. R is taking a lot of time performing this operation.
Is there any alternate way to perform cbind?
x =
y = table2[1:1000000,5]
z = cbind(x,y) //hanging the machine
You should have been able to bypass the intermediate steps with just:
z = cbind( table1[1:1000000,1] table2[1:1000000,5])
Whether you will have sufficient contiguous memory for that object at
the moment or even after rm(x), rm(y) is in doubt, but had you not
created the unneeded x and y, you _might_ have succeeded in your
limited environment. (Real answer: Buy more RAM.)
I speculate that you are on Windows and so refer your to the R-Win FAQ
for further reading about memory limits.
write.table(z,'out.txt)
I do not know of a way to bypass the requirement of a named object to
pass to write.table, but testing suggests that you could try:
write( t(cbind( table1[1:1000000,1] table2[1:1000000,5])).
"test.txt", 2)
write() does not require a named object but is less inquisitive than
write table and will give you a transposed matrix with 5 columns by
default which will really mess up things, so you need to transpose and
specify the number of columns. (And that may not save any space over
creating a "z" object.)
So there is another thread today to which master R programmer Bill
Dunlap has offered this strategy (with minor modifications to your
situation by me):
###
f1 <- function (n, fileName) {
unlink(fileName)
system.time({
fileConn <- file(fileName, "wt")
on.exit(close(fileConn))
for (i in seq_len(n)) cat( table1[i, 1], " ",
table2[i, 5],
"\n", file = fileConn)
})
}
f1(1000000, 'out.txt')
#------------
--
David Winsemius, MD
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
