Hi,
I am not sure I follow the scalar part of the suggestion. Could you please
elaborate it a bit more? Each row has a different value of score for each
subject at each time point. Also I simplified the example but there are
other terms that change over each row for each subject.
Does this mean that loops is the only way to go ?
Thanks again for your help and time.
Navin Goyal
On Sun, Apr 8, 2012 at 4:03 AM, Berend Hasselman <b...@xs4all.nl> wrote:
>
> On 08-04-2012, at 08:28, Navin Goyal wrote:
>
> > Dear R users,
> > I am running a loop with the integrate function. I have pasted the code
> > below. I am integrating a function from time=0 to the time value in every
> > row.
> > I have to perform this integration over thousands of rows with different
> > parameters in each row. Could someone please suggest if there is an
> > efficient/faster/easier way to do this by avoiding the loops ?
> >
> > Thank you so much for your help and time.
> > --
> > Navin Goyal
> >
> > #####################
> > dose<-10
> > time<-0:5
> > id<-1:5
> > data1<-expand.grid(id,time,dose)
> > names(data1)<-c("ID","TIME", "DOSE")
> > data1<-data1[order(data1$ID,data1$TIME),]
> >
> > ed<-data1[!duplicated(data1$ID) , c("ID","DOSE")]
> > set.seed(5324123)
> >
> > for (k in 1:length(ed$ID))
> > {
> > ed$base[k]<-100*exp(rnorm(1,0,0.05))
> > ed$drop[k]<-0.2*exp(rnorm(1,0,0.01))
> > ed$frac[k]<-0.5*exp(rnorm(1,0,0.1))
> > }
>
> Why not
>
> ed$base <- 100*exp(rnorm(length(ed$ID), 0, 0.05))
>
> etc.
>
> > comb1<-merge(data1[, c("ID","TIME")], ed)
> > comb2<-comb1
> > comb2$score<-comb2$base*exp(-comb2$drop*comb2$TIME)
> >
> > func1<-function(t,cov1,beta1, change,other)
> > {
> > ifelse(t==0,cov1, cov1*exp(beta1*change+other))
> > }
>
> AFAICS, cov1, beta1, change and other are scalars.
> So when an item of t is == 0 then the function value is cov1 and in all
> other cases it is the same scalar and does not depend on t. So func1 is a
> step function. You could calculate the integral directly.
>
> Berend
>
>
--
Navin Goyal
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