Too large output in R

Question

I am writing a for loop program in RStudio.

When I use the following command,

a <- 10
for (i in c(1:10335) { 
    a <- a + 0.005
    print(a)
}

I get a very large output in console, since the loop runs 10335 times. That large output is also a small fraction of the total output (a few, maybe 1000 or so, values from the last). I also loose my written program in the console. How do I fix this issue? How can I get a complete set of 10335 values in the output?

Also, is there any way to export this output in excel or in text format?

what you want to have for output, your output is natural for the loop you have — Mateusz1981, Dec 14 '16 at 13:03
Are you not typing your code into the source file pane and executing it from there? — nrussell, Dec 14 '16 at 13:04
What is your intention? Try `a <- 10`, `out <- 10 + c(0:9)*0.005` and have a look at `out`. Perhaps you also should have a look at `seq` — Christoph, Dec 14 '16 at 13:07
You can save output to a file. You can store output in a vector (or matrix or dataframe) which can be exported (say as a csv file) which is then imported to Excel. If you store the output to a vector you can use the `View` function to inspect it. As you have discovered, having thousands of print statements is seldom helpful. — John Coleman, Dec 14 '16 at 13:07
@nrussell No, I was trying to do it in console. Even with the source file pane, I am getting the same issue in console. — , Dec 14 '16 at 13:11

Andrew J. Rech · Answer 1 · 2016-12-14T13:29:04.793

2

Instead of printing the values, you can add them to an existing vector:

a <- 10
results <- vector(length = 10335)
for (i in c(1:10335)) {
a <- a + 0.005
results[i] <- a
}

str(results)
num [1:10335] 10 10 10 10 10 ...

You can save the result to a text file using write.table:

write.table(results, file = "results.txt", row.names = FALSE, col.names = FALSE)

edited Dec 14 '16 at 13:29

answered Dec 14 '16 at 13:07

Andrew J. Rech

456
4
11

5

Don't do it this way -- preallocate space for the vector. You have just turned what should be a linear algorithm into a quadratic algorithm. – John Coleman Dec 14 '16 at 13:09
Isn't the whole vector copied on modification whether the length is preallocated or not? – Andrew J. Rech Dec 14 '16 at 13:20
3

No, it isn't. R would be a dreadfully slow language if things worked that way. See the accepted answer to : http://stackoverflow.com/q/12464379/4996248 about how to use `vector` to preallocate. Your answer is otherwise quite good. I'll upvote it if you tweak it (the downvote wasn't by me. by the way). – John Coleman Dec 14 '16 at 13:21

score 2 · Accepted Answer · answered Dec 14 '16 at 13:22

We can avoid for loop using seq():

# using seq instead of forloop
res <- seq(from = 10 + 0.005, to = 10 + 10335 * 0.005, by = 0.005)
# and write to a file
write.table(res, "temp_seq.txt", col.names = FALSE, row.names = FALSE)

Or if we must use loop then use sink() function:

# using loop and sink the output to a file
sink("temp_loop.txt")
a <- 10
for (i in c(1:10335)) { 
  a <- a + 0.005
  print(a)
}
sink()

In both cases we are writing output to a file, as RStudio console has a limits on print.

Too large output in R

2 Answers2