From: Eric C Banfield <ECB2_at_ntrs.com>

Date: Wed, 23 Jul 2008 15:18:07 -0500

Date: Wed, 23 Jul 2008 15:18:07 -0500

Jim, thank you very much This looks like it works.
(I just need to study the code and see if I can understand precisely why
and how it works.)

Eric

"jim holtman" <jholtman_at_gmail.c om> To 07/23/2008 02:56 "Eric C Banfield" <ECB2_at_ntrs.com> PM cc r-help_at_r-project.org Subject Re: [R] Q re iterating a process and appending results to output file

Here is one way of doing it:

# generate 200 x 2500 samples and then check them
c <- qnorm(0.05)

i <- 2500

iter <- 200

x <- matrix(rnorm(i * iter, 0, 1) < c,nrow=i) # TRUE/FALSE according
to condition

# now create the counts

x.c <- colSums(x)

# write out to a file 1 value on each line
cat(x.c, file='/tempxx.txt', sep="\n")

On Wed, Jul 23, 2008 at 2:47 PM, Eric C Banfield <ECB2_at_ntrs.com> wrote:

*>
*

> Greetings. This is very basic but we can't figure it out. The following

*> simple code counts how many values land in the "tail" (below a quantile)
*

of

> a standardized normal distribution of random numbers. First two commands

*> are inputs:
**>> c <-0.05
**>> i <-2500
**> Second two commands are formulas I want to repeat many times (sort of
*

like

> an Excel/VBA macro) using those same inputs:

*>> r <- rnorm(i,0,1)
**>> n <- length(r[r<qnorm(c)])
**>
**> I believe I could also run this as one line: r <- rnorm(i); n <-
**> length(r[r<qnorm(c)])
**>
**> "n" will vary around 125. Each time I run the code -- say 262 times --
**> I'll get a new "n". I want to save all those "n"s in a file for Excel.
**>
**> I can use cat(n,file="c:/temp/file.csv") to store the value of n in a
*

*.csv

> file. But:

*>
**> 1. How do I tell R each time I run the above to append in that file the
*

new

> value of 'n' to the list of prior 'n's?

*> e.g., Suppose the first run I get n=125, second run I get n=127, and so
*

on.

> I want a file that will have 125 in the first row, 127 the second, and so

*> on,
**> I tried cat(n,file="c:/temp/file.csv", sep=" ") but it holds only the
**> single, latest value of n.
**> I tried file.append but then I get 125127.
**>
**> 2. How do I tell R to run or loop through the above lines hundreds of
**> times, e.g., j = 262? -- rather like an Excel/VBA macro?)
**> So if I can make this iterate 262 times, I'll have a list or column of
*

262

> numbers.

*>
**> Thanks -- Eric.
**>
**> ______________________________________________
**> R-help_at_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.
**>
*

-- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem you are trying to solve? ______________________________________________ R-help_at_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.Received on Wed 23 Jul 2008 - 20:23:49 GMT

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