R help - Aug 2011 - problem in do.call function

Dear all,

I am trying to use "do.call", but I don't think I totally
understand this
function.

Here is an simple example.

--------------------------------------------
> B <- matrix(c(.5,.1,.2,.3),2,2)
> B
     [,1] [,2]
[1,]  0.5  0.2
[2,]  0.1  0.3
> x <- c(.1,.2)
> X <- cbind(1,x)
> X
         x
[1,] 1 0.1
[2,] 1 0.2
> 
> lt <- expand.grid(i=seq(1,2), y0=seq(0,2))
> lt
  i y0
1 1  0
2 2  0
3 1  1
4 2  1
5 1  2
6 2  2
> 
> fc <- function(y0,i) dpois(y0, exp(rowSums(t(X[i,])*B[,1])))
> 
> do.call(fc,lt)
[1] 1.892179e-09 3.348160e-01 3.800543e-08 3.663470e-01 3.816797e-07
2.004237e-01

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

Unfortunately, what I want to get is 

dpois(0, exp(rowSums(t(X[1,])*B[,1]))) = 0.1891356
dpois(0, exp(rowSums(t(X[2,])*B[,1]))) = 0.1859965
dpois(1, exp(rowSums(t(X[1,])*B[,1]))) = 0.3149658
dpois(1, exp(rowSums(t(X[2,])*B[,1]))) = 0.3128512
dpois(2, exp(rowSums(t(X[1,])*B[,1]))) = 0.2622549
dpois(2, exp(rowSums(t(X[2,])*B[,1]))) = 0.2631122

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

Would you plz tell me why these two results are different?? and how do I get
what I want to using "do.call" function??


Regards,

Kathryn Lord 

--
View this message in context:
http://r.789695.n4.nabble.com/problem-in-do-call-function-tp3726413p3726413.html
Sent from the R help mailing list archive at Nabble.com.

On 08/08/2011 4:34 AM, Kathie wrote:
> Dear all,
>
> I am trying to use "do.call", but I don't think I totally
understand this
> function.
>
> Here is an simple example.
>
> --------------------------------------------
>
> >  B<- matrix(c(.5,.1,.2,.3),2,2)
> >  B
>       [,1] [,2]
> [1,]  0.5  0.2
> [2,]  0.1  0.3
> >  x<- c(.1,.2)
> >  X<- cbind(1,x)
> >  X
>           x
> [1,] 1 0.1
> [2,] 1 0.2
> >
> >  lt<- expand.grid(i=seq(1,2), y0=seq(0,2))
> >  lt
>    i y0
> 1 1  0
> 2 2  0
> 3 1  1
> 4 2  1
> 5 1  2
> 6 2  2
> >
> >  fc<- function(y0,i) dpois(y0, exp(rowSums(t(X[i,])*B[,1])))
> >
> >  do.call(fc,lt)
> [1] 1.892179e-09 3.348160e-01 3.800543e-08 3.663470e-01 3.816797e-07
> 2.004237e-01
>
> --------------------------------------------
>
> Unfortunately, what I want to get is
>
> dpois(0, exp(rowSums(t(X[1,])*B[,1]))) = 0.1891356
> dpois(0, exp(rowSums(t(X[2,])*B[,1]))) = 0.1859965
> dpois(1, exp(rowSums(t(X[1,])*B[,1]))) = 0.3149658
> dpois(1, exp(rowSums(t(X[2,])*B[,1]))) = 0.3128512
> dpois(2, exp(rowSums(t(X[1,])*B[,1]))) = 0.2622549
> dpois(2, exp(rowSums(t(X[2,])*B[,1]))) = 0.2631122
>
> --------------------------------------------
>
> Would you plz tell me why these two results are different?? and how do I
get
> what I want to using "do.call" function??
Your function expects arguments in the order y0, i, but you are passing 
them in the order i, y0.  Change the header of your function or the 
order of the columns in lt.

Duncan Murdoch