Hi Pedro,

I believe that the following should do what you want:

----start----

# Copy over to fill the NAs
# Gets all Q16.x values that are set to NA, and assigns the equivalent Q16.y
values
f$Q16.x[is.na(f$Q16.x)] <- f$Q16.y[is.na(f$Q16.x)]
f$Q17.x[is.na(f$Q17.x)] <- f$Q17.y[is.na(f$Q17.x)]

# Keep and rename the columns we want
f <- f[,c("NIU", "Q16.x", "Q17.y")]
names(f) <- c("NIU", "Q16", "Q17")

----end----

Let me know if it doesn't work as it should.

-Aidan

On Thu, Jun 24, 2010 at 3:17 PM, Pedro Emmanuel Alvarenga Americano do
Brasil <emmanuel.brasil@gmail.com> wrote:

> Hello R friends,
>
> I would like to know if anyone could give me a tip of a function to merge
> two data frames but updating NA fields. Any script that I could work on
> would be fine too.
>
> I have two datasets which each one is from different physicians evaluating
> the same subjects. The two data frames have the same variables. I woud like
> to merge them but the second data frame 'inputing' its data on the empty
> filds of the first one. I tried the merge function, but it does not work as
> I would like to. I found other merge functions and a combine (Hmisc) but I
> coudnt get it done so far. I did it very long ago using Stata (whith a
> command called joinby), but a I couldnt find any like that in R. An example
> below...
>
>
> >c1
> NIU    Q16  Q17
> 1      SIM  *SIM
> *2      *NA*   NAO
> 3      NAO  SIM
> 4*      NA   NA*
> 5      SIM  NAO
>
> c2
> NIU    Q16  Q17
> 1      SIM  *NAO*
> 2      *NAO*  NAO
> 3      NAO  SIM
> 4  *    SIM  SIM*
> 5      NA   NA
>
> f <- merge(c1,c2,by.x='NIU',by.x='NIU',all.x=T,all.y=F)
> f # using base::merge would give something like this ...
>
> NIU    Q16.x  Q17.x  Q16.y  Q17.y
> 1      SIM    SIM    SIM    NAO
> 2      NA     NAO    NAO    NAO
> 3      NAO    SIM    NAO    SIM
> 4      NA     NA     SIM    SIM
>  5      SIM    NAO    NA     NA
>
>
> f # but I would like something like this...
>
> NIU    Q16  Q17
> 1      SIM  *SIM
> *2      *NAO*  NAO
> 3      NAO  SIM
> 4      SIM  SIM
> 5      SIM  NAO
>
> Any tip?
>
> Kind regards,
>
> Abraço forte e que a força esteja com você,
>
> Dr. Pedro Emmanuel A. A. do Brasil
> Instituto de Pesquisa Clínica Evandro Chagas
> Fundação Oswaldo Cruz
> Rio de Janeiro - Brasil
> Av. Brasil 4365
> Tel 55 21 3865-9648
> email: pedro.brasil@ipec.fiocruz.br
> email: emmanuel.brasil@gmail.com
>
> ---Apoio aos softwares livres
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> www.broffice.org ou www.openoffice.org - textos, planilhas ou
> apresentações.
> www.epidata.dk - entrada de dados.
> www.r-project.org - análise de dados.
> www.ubuntu.com/ - sistema operacional
>
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>
>
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>
>

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