R help - Jul 2010 - Data frame modification

Hi

I am trying to modify a data frame D with lists x and y in such a way that if a
value in x==0 then it should replace that value with the last not zero value in
x. I.e.
 
for loop over i{
if(D$x[i]==0)
     D$x[i]=D$x[i-1]
}

The data frame is quite large in size ~ 43000 rows. This operation is taking a
large amount of time. Can someone please suggest me what might be the reason.

Thanks
Regards
Siddharth
Sent on my BlackBerry? from Vodafone

Hi

r-help-bounces at r-project.org napsal dne 28.07.2010 11:30:48:
> Hi
> 
> I am trying to modify a data frame D with lists x and y in such a way 
that if 
> a value in x==0 then it should replace that value with the last not zero 
valuein x. I.e.
> 
> for loop over i{
> if(D$x[i]==0)
>      D$x[i]=D$x[i-1]
> }
> 
> The data frame is quite large in size ~ 43000 rows. This operation is 
taking a
> large amount of time. Can someone please suggest me what might be the 
reason.

Bad programming practice? I would suggest to use zoo package and na.locf 
function after changing all zero values to NA.

Regards
Petr
> 
> Thanks
> Regards
> Siddharth
> Sent on my BlackBerry? from Vodafone
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