R help - Jun 2009 - Merge data frame and keep unmatched

Hi,

With two data sets, one complete and another one partial, I would like to
merge them and keep the unmatched lines. The problem is that merge() dosen't
keep the unmatched lines. Is there another function that I could use to
merge the data frames.

Example:

completedf <- expand.grid(alpha=letters[1:3],beta=1:3)
partdf <- data.frame(
	alpha= c('a','a','c'),
	beta = c(1,3,2),
	val = c(2,6,4))

mergedf <- merge(x=completedf, y=partdf,
by=c('alpha','beta'))
# it only kept the common rows
nrow(mergedf)

Thanks, 
Etienne
-- 
View this message in context:
http://www.nabble.com/Merge-data-frame-and-keep-unmatched-tp23962874p23962874.html
Sent from the R help mailing list archive at Nabble.com.

On Jun 10, 2009, at 8:56 AM, Etienne B. Racine wrote:
>
> Hi,
>
> With two data sets, one complete and another one partial, I would  
> like to
> merge them and keep the unmatched lines. The problem is that merge()  
> dosen't
> keep the unmatched lines. Is there another function that I could use  
> to
> merge the data frames.
>
> Example:
>
> completedf <- expand.grid(alpha=letters[1:3],beta=1:3)
> partdf <- data.frame(
> 	alpha= c('a','a','c'),
> 	beta = c(1,3,2),
> 	val = c(2,6,4))
>
> mergedf <- merge(x=completedf, y=partdf,
by=c('alpha','beta'))
> # it only kept the common rows
> nrow(mergedf)
>
> Thanks,
> Etienne


Is this what you want?

 > merge(x=completedf, y=partdf, by=c('alpha','beta'), all =
TRUE)
   alpha beta val
1     a    1   2
2     a    2  NA
3     a    3   6
4     b    1  NA
5     b    2  NA
6     b    3  NA
7     c    1  NA
8     c    2   4
9     c    3  NA

Note the 'all', 'all.x' and 'all.y' arguments...

HTH,

Marc Schwartz

Try:

merge(completedf, partdf, all.x = TRUE)

or

library(sqldf) # see http://sqldf.googlecode.com
sqldf("select * from completedf left join partdf using(beta, alpha)")


On Wed, Jun 10, 2009 at 9:56 AM, Etienne B. Racine<etiennebr at gmail.com>
wrote:
>
> Hi,
>
> With two data sets, one complete and another one partial, I would like to
> merge them and keep the unmatched lines. The problem is that merge()
dosen't
> keep the unmatched lines. Is there another function that I could use to
> merge the data frames.
>
> Example:
>
> completedf <- expand.grid(alpha=letters[1:3],beta=1:3)
> partdf <- data.frame(
> ? ? ? ?alpha= c('a','a','c'),
> ? ? ? ?beta = c(1,3,2),
> ? ? ? ?val = c(2,6,4))
>
> mergedf <- merge(x=completedf, y=partdf,
by=c('alpha','beta'))
> # it only kept the common rows
> nrow(mergedf)
>
> Thanks,
> Etienne
> --
> View this message in context:
http://www.nabble.com/Merge-data-frame-and-keep-unmatched-tp23962874p23962874.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.
>