Hi all,
I am trying to figure out a way to improve my code's efficiency by avoiding
the use of loop.
I want to calculate a conditional mean(?) given time.
For example, from the data below, I want to calculate
sum((value|choice==1)/sum(value)) across time.
Is there a way to do it without using a loop?
time cum_time choice value
1 4 1 3
1 4 0 2
1 4 0 3
1 4 0 3
2 6 1 4
2 6 0 4
2 6 0 2
2 6 0 4
2 6 0 2
2 6 0 2
3 4 1 2
3 4 0 3
3 4 0 5
3 4 0 2
My code looks like
objective[1] = value[1] / sum(value[1:cum_time[1])
for (i in 2:max(time)){
objective[i] = value[cum_time[i-1]+1] / sum(value[(cum_time[i-1]+1) :
cum_time[i])])
}
sum(objective)
Anyone have an idea that I can do this without using a loop??
Thanks.
_________________________________________________________________
[[elided Hotmail spam]]
[[alternative HTML version deleted]]
one approach is the following:
# say 'DF' is your data frame, then
with(DF, {
ind <- choice == 1
n <- tapply(value[ind], time[ind], sum)
d <- tapply(value, time, sum)
n / d
})
I hope it helps.
Best,
Dimitris
parkbomee wrote:> Hi all,
>
> I am trying to figure out a way to improve my code's efficiency by
avoiding the use of loop.
> I want to calculate a conditional mean(?) given time.
> For example, from the data below, I want to calculate
sum((value|choice==1)/sum(value)) across time.
> Is there a way to do it without using a loop?
>
> time cum_time choice value
> 1 4 1 3
> 1 4 0 2
> 1 4 0 3
> 1 4 0 3
> 2 6 1 4
> 2 6 0 4
> 2 6 0 2
> 2 6 0 4
> 2 6 0 2
> 2 6 0 2
> 3 4 1 2
> 3 4 0 3
> 3 4 0 5
> 3 4 0 2
>
>
>
> My code looks like
>
> objective[1] = value[1] / sum(value[1:cum_time[1])
> for (i in 2:max(time)){
> objective[i] = value[cum_time[i-1]+1] / sum(value[(cum_time[i-1]+1) :
cum_time[i])])
> }
> sum(objective)
>
>
> Anyone have an idea that I can do this without using a loop??
> Thanks.
>
>
> _________________________________________________________________
> [[elided Hotmail spam]]
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014