[R] Ids with matching number combinations?

[Jim Lemon]

Hi Marine,
I'm not sure that I have the right idea, but this worked for me and may help.

# I had to fix this line
df<-data.frame(id=rep(1:10,each=10),item1=sample(1:20, 100, replace=TRUE))
df2<-data.frame(a=c(8, 8,10,9, 5, 1,2,1),b=c(16,18,11, 19,18, 11,17,12))
result<-data.frame(id=df[,1],rown=1:dim(df)[1],matched=rep(FALSE,dim(dfw)[1]))
# function that checks that all entries in vector a exist in vector x
match_all_a<-function(a,x,index) {
 inx<-TRUE
 for(i in 1:length(a)) inx <- inx && a[i] %in% x[-1]
 return(list(id=x[1],rown=index,matched=inx))
}
# step through the data frame
for(i in df[,1]) result[i,]<-match_all_a(df2[i,],df[i,],i)
# display the result id, row in df, whether matched
result
# select the rows of result for which matched is TRUE

Jim

On Fri, Oct 7, 2022 at 11:57 PM Marine Andersson <marine.andersson using ki.se> wrote:
>
> Hi,
>
> If I have two datasets like this:
> df=data.frame("id"=rep(1:10,10, each=10), "item1"=sample(1:20, 100, replace=T)
> df2=data.frame("a"=c(8, 8,10,9, 5, 1,2,1), "b"=c(16,18,11, 19,18, 11,17,12))
>
> How do I find out which ids in the df dataset that has a match for both the numbers occuring in the same row in the df2 dataframe? In the output I would like to get the matching id and the rownumber from the df2.
>
> Output something like this
> Id                        Rownr
> 2                         1
> 5                         1
> 7                         4
>
> My actual problem is more complex with even more columns to be matched and the datasets are large, hence the solution needs to be efficient.
>
> Kind regards,
>
>
>
>
>
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