R help - Sep 2008 - selecting from a series of integers with pre-determined probabilities

R 2.6
Windows XP

I need to select from the integers 1,2,3,4,5 with some pre-determined
probability, e.g. probability of selecting 5 80%, probability of selecting 1 or 
2 or  3 or 4 20%. Any suggestions for how I might accomplish this? I need to do
it very efficiently as I will be doing it 500,000 times.
Thanks
John

John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)

Confidentiality Statement:
This email message, including any attachments, is for th...{{dropped:6}}

?sample

efficient enough?> system.time(z <- sample(1:5, 500000, TRUE,
prob=c(.05,.05,.05,.05,.8)))
   user  system elapsed
   0.12    0.02    0.14
> table(z)
z
     1      2      3      4      5
 24800  24771  25039  25022 400368
>

On Sat, Sep 20, 2008 at 3:43 PM, John Sorkin
<jsorkin@grecc.umaryland.edu>wrote:
> R 2.6
> Windows XP
>
> I need to select from the integers 1,2,3,4,5 with some pre-determined
> probability, e.g. probability of selecting 5 80%, probability of selecting
1
> or  2 or  3 or 4 20%. Any suggestions for how I might accomplish this? I
> need to do it very efficiently as I will be doing it 500,000 times.
> Thanks
> John
>
> John David Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
> Confidentiality Statement:
> This email message, including any attachments, is for ...{{dropped:22}}

?sample.

-- Bert Gunter

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On
Behalf Of John Sorkin
Sent: Saturday, September 20, 2008 12:43 PM
To: r-help at r-project.org
Subject: [R] selecting from a series of integers withpre-determined
probabilities

R 2.6
Windows XP

I need to select from the integers 1,2,3,4,5 with some pre-determined
probability, e.g. probability of selecting 5 80%, probability of selecting 1
or  2 or  3 or 4 20%. Any suggestions for how I might accomplish this? I
need to do it very efficiently as I will be doing it 500,000 times.
Thanks
John

John David Sorkin M.D., Ph.D.
Chief, Biostatistics and Informatics
University of Maryland School of Medicine Division of Gerontology
Baltimore VA Medical Center
10 North Greene Street
GRECC (BT/18/GR)
Baltimore, MD 21201-1524
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)

Confidentiality Statement:
This email message, including any attachments, is for th...{{dropped:8}}