Re: [R] Looking for simpler solution to probabilistic question

2008-01-15 Thread Berwin A Turlach 
G'day Rainer,

On Tue, 15 Jan 2008 14:24:08 +0200
Rainer M Krug [EMAIL PROTECTED] wrote:

 I have two processes which take with a certain probability (p1 and
 p2) x number of years to complete (age1 and age2). As soon as thge
 first process is completed, the second one begins. I want to
 calculate the time it takes for the both processes to be completed.
 
 I have the following script which gives me the answer, butI think
 there must be a more elegant way of doing the calculations between
 the #

The code between the  together with the first line after the second
 could be just shortened to:

 ager - range(age1) + range(age2)
 ager - ager[1]:ager[2]
 pp1 - c(cumsum(p1), rev(cumsum(rev(p1
 pp2 - c(cumsum(p2[-21]), rev(cumsum(rev(p2)))[-1])
 pr - pp1+pp2
 pr - pr/sum(pr)

 all.equal(p, pr)
[1] TRUE
 all.equal(age, ager)
[1] TRUE


If this is more elegant is probably in the eye of the beholder, but it
should definitely use less memory. :)

BTW, I am intrigued, in which situation does this problem arise?  The
time it takes the second process to finish seems to depend in a curious
way on the time it took the first process to complete.

Cheers,

Berwin

=== Full address =
Berwin A TurlachTel.: +65 6516 4416 (secr)
Dept of Statistics and Applied Probability+65 6516 6650 (self)
Faculty of Science  FAX : +65 6872 3919   
National University of Singapore 
6 Science Drive 2, Blk S16, Level 7  e-mail: [EMAIL PROTECTED]
Singapore 117546http://www.stat.nus.edu.sg/~statba

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Re: [R] Looking for simpler solution to probabilistic question

2008-01-15 Thread Rainer M Krug 
Berwin A Turlach wrote:
 G'day Rainer,
 
 On Tue, 15 Jan 2008 14:24:08 +0200
 Rainer M Krug [EMAIL PROTECTED] wrote:
 

 
 ager - range(age1) + range(age2)
 ager - ager[1]:ager[2]
 pp1 - c(cumsum(p1), rev(cumsum(rev(p1
 pp2 - c(cumsum(p2[-21]), rev(cumsum(rev(p2)))[-1])
 pr - pp1+pp2
 pr - pr/sum(pr)
 
 all.equal(p, pr)
 [1] TRUE
 all.equal(age, ager)
 [1] TRUE
 
 
 If this is more elegant is probably in the eye of the beholder, but it
 should definitely use less memory. :)

Thanks - interesting approach which is different to using the outer()

 
 BTW, I am intrigued, in which situation does this problem arise?  The
 time it takes the second process to finish seems to depend in a curious
 way on the time it took the first process to complete.

These are two growth processes, where the first one is seedling growth 
up to a certain X and the second one is adult growth from size X onwards 
until it reaches a given final size.

I hope my calculations fit the process...


 
 Cheers,
 
   Berwin
 
 === Full address =
 Berwin A TurlachTel.: +65 6516 4416 (secr)
 Dept of Statistics and Applied Probability+65 6516 6650 (self)
 Faculty of Science  FAX : +65 6872 3919   
 National University of Singapore 
 6 Science Drive 2, Blk S16, Level 7  e-mail: [EMAIL PROTECTED]
 Singapore 117546http://www.stat.nus.edu.sg/~statba

__
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.