problems with function-formating, please help

please help me.

since 2 days i have tried desperately to find desperately a solution for the following problem:

i have an array of 3 different vectors like:

clustertransformationstabelle[,15:17]
          x1            x2                x3
1  0.6270023 0.2464946 0.5074781
2  0.5629291 0.1783861 0.4398626
3  0.6773455 0.3107641 0.5637289
4  0.0000000 0.0000000 0.0000000

i want to calculate a corresponding result-vector with a formula resp function eg:

result <- - 1.60638946783994e-05 + 384.649339378693 * x1 - 168.920548209815 * x2 - 693.51261768584 * x3 + 479.305764753298 * x1 * x3

after formating the result would look like

dim(result) <- c(4,1)
result
               [,1]
 [1,]  1.057852e-01
 [2,]  2.854227e-02
 [3,]  1.107150e-01
 [4,] -1.606389e-05

fine....
but due to mass routines, i have to create the result-function automatically, 
unfortunately it can only be generated via a paste-command as a character-string in quotes like:

functionterm <- "- 1.60638946783994e-05 + 384.649339378693 * x1 - 168.920548209815 * x2 - 693.51261768584 * x3 + 479.305764753298 * x1 * x3"
You should almost never write text and reparse it -- it almost always 
indicates  a poor solution to whatever problem you're trying to solve.

I can't tell from your message what you want your function to do, but if 
you want a function that takes args x1, x2, x3 and returns the value 
1.60638946783994e-05 + 384.649339378693 * x1 - 168.920548209815 * x2 - 
693.51261768584 * x3 + 479.305764753298 * x1 * x3, where those 
coefficients come from some other calculation, just do it like this:

makefn <- function(coeffs) {
   function(x1, x2, x3) coeffs[1] +
                        coeffs[2]*x1 +
                        coeffs[3]*x2 +
                        coeffs[4]*x1*x3
}

Then use it like this:

f <- makefn(c(-1.606, 384.64, etc.))

and f is the function you want.

Duncan Murdoch
how on earth can i use that automatically generated functionterm (see line above), 
unfortunately inclusive their quotes, in order to get a correct fomated function?

if i try to convert it into a function like:

result <- as.function(alist(x1=,x2=,x3=, functionterm))

and give some example input-data eg.:

result(0.6270023, 0.2464946, 0.5074781)

i always get that stupid functionterm in quotes returned
[1] "- 1.60638946783994e-05 + 384.649339378693 * x1 - 168.920548209815 * x2 - 693.51261768584 * x3 + 479.305764753298 * x1 * x3"

instead of the correct values (like 1.057852e-01, see result-array[1,1] some lines above)
please help me, i am blocked since 2 days already by that stupid problem

joerg burmester

Phone: +49-(0)4131-40898-5
Mobile Phone: +49-(0)177-4812371
Fax: +49-(0)4131-40898-7
Email: joerg-burmester at gmx.net

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problems with function-formating, please help

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