Loop question?

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]]



------------------------------------------------------------------------

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]]

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? ? ? ? ? ?
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???.....? Go Live...
DCN:<jdnewmil at dcn.davis.ca.us>?
? ? ? Basics: ##.#.? ?
???##.#.? Live Go...
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? ? ? ? ? ? ? ?
? ? ? Live:???OO#.. Dead:
OO#..? Playing
Research Engineer (Solar/Batteries? ? ?
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???#.O#.? with
/Software/Embedded Controllers)? ? ? ?
? ? ???.OO#.? ?
???.OO#.? rocks...1k
---------------------------------------------------------------------------

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]]



------------------------------------------------------------------------

mailing list

reproducible code.

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,

On 26-01-2013, at 12:31, Andras Farkas <motyocska at yahoo.com> wrote:

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,

ab <- expand.grid(a=a,b=b)
z <- unlist(sapply(seq_len(nrow(ab)), function(k)
infcprodessa(ab[k,1],TINF,ab[k,2],ab[k,2]-TINF)))

z.target <- which(z>=15 & z<=20)
ab[z.target,]
z[z.target]
which.min(ab[z.target,][,"a"])

Berend