R help - Oct 2006 - update index in "for" statement during calculation

Hello,

I have a time series of data as a data.frame. Occasionally there is 
one or more days missing (e.g. data available for days 2, 3, 4, 8, 9, 
10 --> missing days between 4 and 8). The experimental time 
information can be found in the 2nd column of "data". I would like to 
have a continuous time line with one time point per day. Therefore I 
try to insert lines for the missing days that contain zeros for the 
data categories just to fill the columns.

In most cases the code below works fine but there is one problem: 
Since apparently the "for" statement does not get updated with the 
exanding data.frame "data" (as lines get inserted), the
"for"
statement ends somewhere before the end of the now longer modified 
version of "data". Therefore potential missing data points afterwards 
are not inserted any longer.

Does anybody know how I can update the information on "i" in the 
"for" statement along the way of the calculation? Or does anybody 
know a way around my problem?

Thanks already,

Kim

### Code ###

for (i in 1:(nrow(data)-1))
{
     diff.time    <- round(data[i+1,2], 0) - round(data[i,2], 0)-1
     old.row              <-  nrow(data)
     if (diff.time > 0)
             {
                 fill                <-  c(data[i,1], 
(round(data[i,2], 0)+1), rep(0,classnumber))
                 data        <-  rbind(data[1:i,], fill,
data[(i+1):old.row,])
             }
}

__________________________________________

Kim Milferstedt
University of Illinois at Urbana-Champaign
Department of Civil and Environmental Engineering
4125 Newmark Civil Engineering Laboratory
205 North Mathews Avenue MC-250
Urbana, IL 61801
USA
phone: (001) 217 333-9663
fax: (001) 217 333-6968
email: milferst at uiuc.edu
http://cee.uiuc.edu/research/morgenroth

try using a 'while':

i <- 1
while (i < nrow(data) - 1)
{
    diff.time    <- round(data[i+1,2], 0) - round(data[i,2], 0)-1
    old.row              <-  nrow(data)
    if (diff.time > 0)
            {
                fill                <-  c(data[i,1],
(round(data[i,2], 0)+1), rep(0,classnumber))
                data        <-  rbind(data[1:i,], fill, data[(i+1):old.row
,])
            }
    i <- i+1
}




On 10/25/06, Kim Milferstedt <milferst@uiuc.edu>
wrote:
>
> Hello,
>
> I have a time series of data as a data.frame. Occasionally there is
> one or more days missing (e.g. data available for days 2, 3, 4, 8, 9,
> 10 --> missing days between 4 and 8). The experimental time
> information can be found in the 2nd column of "data". I would
like to
> have a continuous time line with one time point per day. Therefore I
> try to insert lines for the missing days that contain zeros for the
> data categories just to fill the columns.
>
> In most cases the code below works fine but there is one problem:
> Since apparently the "for" statement does not get updated with
the
> exanding data.frame "data" (as lines get inserted), the
"for"
> statement ends somewhere before the end of the now longer modified
> version of "data". Therefore potential missing data points
afterwards
> are not inserted any longer.
>
> Does anybody know how I can update the information on "i" in the
> "for" statement along the way of the calculation? Or does anybody
> know a way around my problem?
>
> Thanks already,
>
> Kim
>
> ### Code ###
>
> for (i in 1:(nrow(data)-1))
> {
>     diff.time    <- round(data[i+1,2], 0) - round(data[i,2], 0)-1
>     old.row              <-  nrow(data)
>     if (diff.time > 0)
>             {
>                 fill                <-  c(data[i,1],
> (round(data[i,2], 0)+1), rep(0,classnumber))
>                 data        <-  rbind(data[1:i,], fill,
data[(i+1):old.row
> ,])
>             }
> }
>
> __________________________________________
>
> Kim Milferstedt
> University of Illinois at Urbana-Champaign
> Department of Civil and Environmental Engineering
> 4125 Newmark Civil Engineering Laboratory
> 205 North Mathews Avenue MC-250
> Urbana, IL 61801
> USA
> phone: (001) 217 333-9663
> fax: (001) 217 333-6968
> email: milferst@uiuc.edu
> http://cee.uiuc.edu/research/morgenroth
>
> ______________________________________________
> R-help@stat.math.ethz.ch 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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?

	[[alternative HTML version deleted]]

Kim Milferstedt <milferst <at> uiuc.edu> writes:
> 
> Hello,
> 
> I have a time series of data as a data.frame. Occasionally there is 
> one or more days missing (e.g. data available for days 2, 3, 4, 8, 9, 
> 10 --> missing days between 4 and 8). The experimental time 
> information can be found in the 2nd column of "data". I would
like to
> have a continuous time line with one time point per day. Therefore I 
> try to insert lines for the missing days that contain zeros for the 
> data categories just to fill the columns.
> 
<SNIP>
> 
> Thanks already,
> 
> Kim
> 
<SNIP>

I believe this will also do what you want:
> days<-c(1:10)[-5:-7]
> xx<-rnorm(7)
> data<-data.frame(xx,days)
> new.data<-merge(data,data.frame(days=1:10),all.y=TRUE)
It usually is not a good idea to use zeroes as placeholders for missing values.

Mark Lyman