R help - Sep 2011 - Generalizing call to function

Hello guys,

I would like to ask for help to understand what is going on in
"func2". My plan is to generalize "func1", so that are
expected same
results in "func2" as in "func1". Executing
"func1" returns...

0.25 with absolute error < 8.4e-05

But for "func2" I get...

Error in dpois(1, 0.1, 23.3065168689948, 0.000429064542600244,
3.82988398013855,  :
 unused argument(s) (0.000429064542600244, 3.82988398013855,
0.00261104515224461, 1.37999516465199, 0.0072464022020844,
0.673787740945863, 0.0148414691931943, 0.383193602946711,
0.0260964690514175, 0.236612585866545, 0.0422631787036055,
0.152456705113438, 0.0655923922306948)

Thanks in advance.

func1 <- function(y, a, rate) {
       f1 <- function(n, y, a, rate) {
               lambda <- a * n
               dexp(n, rate) * dpois(y, lambda)
       }
       integrate(f1, 0, Inf, y, a, rate)
}

func1(1, 0.1, 0.1)


func2 <- function(y, a, rate, samp) {
       f1 <- function(n, y, a, rate, samp) {

               SampDist <- function(y, a, n, samp) {
                       lambda <- a * n
                       dcom <- paste("d", samp, sep="")
                       dots <- as.list(c(y, lambda))
                       do.call(dcom, dots)
               }

               dexp(n, rate) * SampDist(y, a, n, samp)
       }
       integrate(f1, 0, Inf, y, a, rate, samp)
}

func2(1, 0.1, 0.1, "pois")

Try this:

funa <- function(n, y, a, rate, samp) { 
        lambda <- a * n 
        dexp(n, rate) * do.call(paste("d", samp, sep=""), y,
lambda)
        }

funb <- function(y, a, rate, samp) { 
        integrate(f1, 0, Inf, y, a, rate) 
        } 

funb(1, 0.1, 0.1, "pois") 

Jean

> 
> Hello guys,
> 
> I would like to ask for help to understand what is going on in
> "func2". My plan is to generalize "func1", so that are
expected same
> results in "func2" as in "func1". Executing
"func1" returns...
> 
> 0.25 with absolute error < 8.4e-05
> 
> But for "func2" I get...
> 
> Error in dpois(1, 0.1, 23.3065168689948, 0.000429064542600244,
> 3.82988398013855,  :
>  unused argument(s) (0.000429064542600244, 3.82988398013855,
> 0.00261104515224461, 1.37999516465199, 0.0072464022020844,
> 0.673787740945863, 0.0148414691931943, 0.383193602946711,
> 0.0260964690514175, 0.236612585866545, 0.0422631787036055,
> 0.152456705113438, 0.0655923922306948)
> 
> Thanks in advance.
> 
> func1 <- function(y, a, rate) {
>        f1 <- function(n, y, a, rate) {
>                lambda <- a * n
>                dexp(n, rate) * dpois(y, lambda)
>        }
>        integrate(f1, 0, Inf, y, a, rate)
> }
> 
> func1(1, 0.1, 0.1)
> 
> 
> func2 <- function(y, a, rate, samp) {
>        f1 <- function(n, y, a, rate, samp) {
> 
>                SampDist <- function(y, a, n, samp) {
>                        lambda <- a * n
>                        dcom <- paste("d", samp,
sep="")
>                        dots <- as.list(c(y, lambda))
>                        do.call(dcom, dots)
>                }
> 
>                dexp(n, rate) * SampDist(y, a, n, samp)
>        }
>        integrate(f1, 0, Inf, y, a, rate, samp)
> }
> 
> func2(1, 0.1, 0.1, "pois")
	[[alternative HTML version deleted]]

. wrote:
> 
> Hello guys,
> 
> I would like to ask for help to understand what is going on in
> "func2". My plan is to generalize "func1", so that are
expected same
> results in "func2" as in "func1". Executing
"func1" returns...
> 
> 0.25 with absolute error < 8.4e-05
> 
> But for "func2" I get...
> 
> Error in dpois(1, 0.1, 23.3065168689948, 0.000429064542600244,
> 3.82988398013855,  :
>  unused argument(s) (0.000429064542600244, 3.82988398013855,
> 0.00261104515224461, 1.37999516465199, 0.0072464022020844,
> 0.673787740945863, 0.0148414691931943, 0.383193602946711,
> 0.0260964690514175, 0.236612585866545, 0.0422631787036055,
> 0.152456705113438, 0.0655923922306948)
> 
> Thanks in advance.
> 
> func1 <- function(y, a, rate) {
>        f1 <- function(n, y, a, rate) {
>                lambda <- a * n
>                dexp(n, rate) * dpois(y, lambda)
>        }
>        integrate(f1, 0, Inf, y, a, rate)
> }
> 
> func1(1, 0.1, 0.1)
> 
> 
> func2 <- function(y, a, rate, samp) {
>        f1 <- function(n, y, a, rate, samp) {
> 
>                SampDist <- function(y, a, n, samp) {
>                        lambda <- a * n
>                        dcom <- paste("d", samp,
sep="")
>                        dots <- as.list(c(y, lambda))
>                        do.call(dcom, dots)
>                }
> 
>                dexp(n, rate) * SampDist(y, a, n, samp)
>        }
>        integrate(f1, 0, Inf, y, a, rate, samp)
> }
> 
> func2(1, 0.1, 0.1, "pois")
> 
You need to replace the line with "dots <- as.list(c(y, lambda))"
with this

dots <- list(y, lambda)

You could also replace the two lines

         dots <- as.list(c(y, lambda))
         do.call(dcom, dots)

with the single line

         do.call(dcom, list(y, lambda)) 

See the description of the argument "args" of do.call.

You should now get the same answer as for func1.
Deciding if this is correct is up to you.

Berend


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