[R] Loop problem

[jim holtman]

Basically you are moving the data up and then incrementing to the next
row.  Here is an example; assume that you are at the 2nd entry:

1
2 <== here
3
4

Now your loop index is 2 and you remove the current data ('2') and are
left with:

1
3  <==  index of 2 points here
4

Now you increment the index to 3 and you get

1
3
4 <== now here

So you have skipped 3.  What you should be doing is determining all
the index values that meet your criteria and then deleting them all at
once, or start from the bottom of the dataframe and work up.

On 3/26/08, Jamie Ledingham <jamie.ledingham at newcastle.ac.uk> wrote:
> Dear all, I have a problem with a loop, if anyone has any knowledge on
> these things I would appreciate some comments.  The code below is
> designed to allow me to extract the top record of the data frame, and
> them remove rows from the data frame which have an index close to the
> extracted top record.
>
>
> topstorm<-subset(rankeddataset[1,]) ## Extracts the top storm
> topstormindex<-rankeddataset[1,1] ## Finds the top storm start index
> startindex<-topstormindex-48 ## sets the start and end indexes
> endindex<-topstorminde+48
> rankeddataset<-rankeddataset[-1,] ## Creates a new list with the top
> storm removed
>
> ##This section of code needs looped.  It removes storms from the list
> which are too close to the extracted storm
>
> for (i in 1:30){
> if (rankeddataset[i,1]>startindex && rankeddataset[i,1]<endindex)
> {rankeddataset<-rankeddataset[-i,]}
> }
>
> Here is some example data:
>
>   82856  15 / 6 / 1966   82856:82879            25.9
>   82857  15 / 6 / 1966   82857:82880            20.5
>   83036  23 / 6 / 1966   83036:83059            17.3
>   87250 15 / 12 / 1966   87250:87273            15.9
>
> The loop does not currently work, it seems to remove every second line
> or so.  Can anyone suggest why this might be, I'm not particularly
> experienced in using loops so it may be a rookie mistake.  Thanks in
> advance.
> Jamie Ledingham
>
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>


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

What is the problem you are trying to solve?