R help - Jun 2010 - using R to draw over a distribution.

Hi,

Suppose I analyze a log to create a histogram:

event E1 occurred N1 times
event E2 occurred N2 times
  ...
  ... for m total events
  ...
event Em occurred Nm times

The total number of occurrences is: T = Sum    Nj
                                        j=1..m

I want to give this histogram to R and ask it to produce T random events such
that approximately N1 instances of E1 are drawn, N2 instances of E2 drawn, and
so forth.

Regards,
Shane

On Jun 14, 2010, at 10:42 AM, SHANE MILLER, BLOOMBERG/ 731 LEXIN wrote:
> Hi,
>
> Suppose I analyze a log to create a histogram:
>
> event E1 occurred N1 times
> event E2 occurred N2 times
>  ...
>  ... for m total events
>  ...
> event Em occurred Nm times
>
> The total number of occurrences is: T = Sum    Nj
>                                        j=1..m
>
> I want to give this histogram to R and ask it to produce T random  
> events such that approximately N1 instances of E1 are drawn, N2  
> instances of E2 drawn, and so forth.
?table  # or perhaps use the fact that hist() will return a table of a  
particular type.
?sample  # from the events with prob = frequencies/T

(If you insist on constraining the total count to be the observed sum  
it will no longer be random with m degrees of freedom. And there are  
many postings on how to do this in the archives.)

-- 

David Winsemius, MD
West Hartford, CT