[R] merging 2 frames while keeping all the entries from the "reference" frame

[Dimitri Liakhovitski]

To clarify just in case, here is the result I am trying to get:

mydate	group	values
12/29/2008	Group1	0.453466522
1/5/2009	Group1	NA
1/12/2009	Group1	0.416548943
1/19/2009	Group1	2.066275155
1/26/2009	Group1	2.037729638
2/2/2009	Group1	-0.598040483
2/9/2009	Group1	1.658999227
2/16/2009	Group1	-0.869325211
12/29/2008	Group2	NA
1/5/2009	Group2	NA
1/12/2009	Group2	NA
1/19/2009	Group2	0.375284194
1/26/2009	Group2	0.706785401
2/2/2009	Group2	NA
2/9/2009	Group2	2.104937151
2/16/2009	Group2	2.880393978



On Mon, Apr 4, 2011 at 1:09 PM, Dimitri Liakhovitski
<dimitri.liakhovitski at gmail.com> wrote:
> Hello!
> I have my data frame "mydata" (below) and data frame "reference" -
> that contains all the dates I would like to be present in the final
> data frame.
> I am trying to merge them so that the the result data frame contains
> all 8 dates in both subgroups (i.e., Group1 should have 8 rows and
> Group2 too). But when I merge it it's not coming out this way. Any
> hint would be greatly appreciated!
> Dimitri
>
> mydata<-data.frame(mydate=rep(seq(as.Date("2008-12-29"), length = 8,
> by = "week"),2),
> group=c(rep("Group1",8),rep("Group2",8)),values=rnorm(16,1,1))
> (reference);(mydata)
> set.seed(1234)
> out<-sample(1:16,5,replace=F)
> mydata<-mydata[-out,]; dim(mydata)
> (mydata)
>
> # "reference" contains the dates I want to be present in the final data frame:
> reference<-data.frame(mydate=seq(as.Date("2008-12-29"), length = 8, by
> = "week"))
>
> # Merging:
> new.data<-merge(mydata,reference,by="mydate",all.x=T,all.y=T)
> new.data<-new.data[order(new.data$group,new.data$mydate),]
> (new.data)
> # my new.data contains only 7 rows in Group 1 and 4 rows in Group 2
>
>
> --
> Dimitri Liakhovitski
> Ninah Consulting
>



-- 
Dimitri Liakhovitski
Ninah Consulting
www.ninah.com