[R] Loop question?

[Andras Farkas]

Sorry Jeff, probably the new version of Yahoo mail doing the html, I switched back to the older one hope that takes care of the problem. Let me clarify the code below:

TINF <-1
a <-c(500,750,1000,1250,1500,1750,2000)
b <-c(8,12,18,24,36,48,60,72,96)

infcprodessa <-function (D, tin, tau, ts) 
     (D * (1 - exp(-0.048 * tin))/(tin * (0.048*79) * (1 - exp(-0.048 * tau)))) * exp(-0.048 * (ts - tin))

z <-sapply(1:1, function(n) infcprodessa(a,TINF,b,b-TINF)) 

so I am looking to find the combination of a = 1000 and b = 12, which iz a value for "z" that would fall between 15 and 20. Sometimes though there may be more than one combinations that will meet criteria, in that case I would like to select the combination based on the smallest "a" value that has the respective "b" value to meet the criteria,

sorry for the confusion,

thanks,

Andras


--- On Sat, 1/26/13, Jeff Newmiller <jdnewmil at dcn.davis.CA.us> wrote:

> From: Jeff Newmiller <jdnewmil at dcn.davis.CA.us>
> Subject: Re: [R] Loop question?
> To: "Andras Farkas" <motyocska at yahoo.com>, "r-help at r-project.org" <r-help at r-project.org>
> Date: Saturday, January 26, 2013, 2:09 AM
> Please read the Posting Guide
> no html email
> reproducible example please
> 
> In general, you can use expand.grid to generate all
> combinations of inputs, compute results as a vector just as
> long as the expand.grid data frame has rows, and identify
> which results meet your criteria by a logical test, and use
> that test to identify which input combinations worked.
> Provide a working starting point and someone might give you
> working code as an answer. (where do a and b come into your
> problem?)
> ---------------------------------------------------------------------------
> Jeff Newmiller           
>             The 
>    .....   
>    .....  Go Live...
> DCN:<jdnewmil at dcn.davis.ca.us> 
>       Basics: ##.#.   
>    ##.#.  Live Go...
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> 
> Sent from my phone. Please excuse my brevity.
> 
> Andras Farkas <motyocska at yahoo.com>
> wrote:
> 
> >Dear All
> >�
> >I have the following data (somewhat simplyfied):
> >�
> >TINF <-1
> >a <-c(500,750,1000,1250,1500,1750,2000)
> >b <-c(8,12,18,24,36,48,60,72,96)
> >�
> >following function:
> >�
> >infcprodessa <-function (D, tin, tau, ts) 
> >� (D * (1 - exp(-0.048 * tin))/(tin * (0.048*79) * (1
> - exp(-0.048 *
> >tau)))) * exp(-0.048 * (ts - tin))
> >
> >z <-sapply(1:1, function(n)
> infcprodessa(1000,TINF,12,12-TINF))
> >�
> >is there a way to select the combination of respective a
> and b values
> >that would result in a calculated z that is between 15
> and 20? In this
> >case the a would be 1000 and the b would be 12 (other
> combinations are
> >also possible), but how could I automatically find them?
> perhaps a
> >loop?
> >�
> >Apreciate the help,
> >�
> >Sincerely,
> >�
> >Andras
> >    [[alternative HTML version deleted]]
> >
> >
> >
> >------------------------------------------------------------------------
> >
> >______________________________________________
> >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.
> 
>