chandu wrote:
>
> I am relatively new to R. I would like to know how can we write the
> realizations (for example generated through rnorm or runif) in to a data
> file. It would be very inefficient to first generate values and then write
> them in to file using "write" function. Instead, is there a way to
> generate 1 value at a time and append them in to the file.
>
"It would be very inefficient". Sounds like you tried it.
n = 30000
system.time(for (i in 1:n){
cat(rnorm(1),file="a.txt",append=TRUE)
}
)
system.time(write.table(rnorm(n),file="b.txt"))
)
user system elapsed
3.98 8.66 16.11
> system.time(write.table(rnorm(n),file="b.txt"))
user system elapsed
0.59 0.01 0.61
So the inefficient method is about 25 times faster.
Dieter
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