[R] Filling in a series

[Gabor Grothendieck]

The zoo package has na.locf (last occurrernce carried foward)
for this purpose:

> x
 [1]  1 NA NA NA NA  2 NA NA NA NA  3 NA NA
> library(zoo)
> na.locf(x)
 [1] 1 1 1 1 1 2 2 2 2 2 3 3 3

On 10/21/06, Dennis Fisher <fisher at plessthan.com> wrote:
> Colleagues
>
> After reading in some clinical data, I discovered that the subject ID
> column contains entries only for the first record for each
> individual; subsequent rows are recorded as NA.  For example:
> > 1
> > NA
> > NA
> > NA
> > NA
> > 2
> > NA
> > NA
> > NA
> > NA
> > 3
> > NA
> > NA
> > ...
>
> I can think of various approaches to replace the NA values with
> appropriate entries.  I could loop through each row - if the value is
> NA, I replace it with the entry from the row above.  Or, I could find
> the positions of the non-NA values with match, then replace groups of
> entries (e.g., positions 2-5) with appropriate entries, again with a
> loop.
>
> But, I expect that R allows some more clever approach to the
> problem.  Any thoughts?
>
> Dennis
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone: 1-866-PLessThan (1-866-753-7784)
> Fax: 1-415-564-2220
> www.PLessThan.com
>
>
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>
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