[R] Speeding things up

[Henrik Bengtsson]

First, since you only update the 'ddtd' conditioned on 'value', you
should be able to vectorize removing the loop.  I let you figure out
how to do that yourself.

Second, you apply the "$" operator multiple times in the loop that
will definitely add some overhead.  It should be faster to extract
'value' and 'ddtd' and work with those instead.

/Henrik

On 1/8/07, Benjamin Dickgiesser <dickgiesser at gmail.com> wrote:
> Hi,
>
> is it possible to do this operation faster? I am going over 35k data
> entries and this takes quite some time.
>
>         for(cnt in 2:length(sdata$date))
>         {
>
>                 if(sdata$value[cnt] < sdata$value[cnt - 1])     {
>                         sdata$ddtd[cnt] <- sdata$ddtd[cnt - 1] + sdata$value[cnt - 1] -
> sdata$value[cnt]
>                 }
>                 else sdata$ddtd[cnt] <- 0
>
>         }
>         return(sdata)
>
> Thank you,
> Benjamin
>
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