# [R] matching type question, please

Erin Hodgess er|nm@hodge@@ @end|ng |rom gm@||@com
Thu Dec 16 23:53:16 CET 2021

```Wow!  These are awesome!  Thanks so much for the special cases!

Erin

On Thu, Dec 16, 2021 at 3:52 PM Rui Barradas <ruipbarradas using sapo.pt> wrote:

> Hello,
>
> And here is another solution, addressing the problem raised by Bert and
> avoiding unique.
>
>
> xr1 <- 8:0
> xr2 <- 0:8
> xs1 <- 9:3
> xs2 <- 4
> cbind(xr1, xr2)[(xr1 %in% xs1) & (xr2 %in% xs2),]
> #xr1 xr2
> #  4   4
>
>
> xr1 <- c(1,2,1)
> xr2 <- c(4,5,4)
> xs1 <- c(6,6)
> xs2 <- c(7,7)
> cbind(xr1, xr2)[(xr1 %in% xs1) & (xr2 %in% xs2),]
> #   xr1 xr2
> (only column names are output)
>
>
> But this only works if the vectors xr* are longer than xs*. Try swapping
> the test values (both sets, Erin's original and Bert's) and see.
>
> So here is a function that checks lengths first, then takes the right
> branch.
>
>
> dupSpecial <- function(x1, x2, y1, y2){
>    if(length(x1) > length(y1)){
>      cbind(x1, x2)[(x1 %in% y1) & (x2 %in% y2),]
>    } else {
>      cbind(y1, y2)[(y1 %in% x1) & (y2 %in% x2),]
>    }
> }
> dupSpecial(xr1, xr2, xs1, xs2)
>
>
> Hope this helps,
>
>
>
> Às 22:01 de 16/12/21, Bert Gunter escreveu:
> > I am not sure Eric's solution is what is wanted:
> >
> > Consider:
> > xr1 <- c(1,2,1)
> > xr2 <- c(4,5,4)
> > xs1 <- c(6,6)
> > xs2 <- c(7,7)
> >
> >> z1 <- cbind(xr1, xr2)
> >> z2 <- cbind(xs1,xs2)
> >> z1
> >       xr1 xr2
> > [1,]   1   4
> > [2,]   2   5
> > [3,]   1   4
> >> z2
> >       xs1 xs2
> > [1,]   6   7
> > [2,]   6   7
> >
> > If what is wanted is to find rows of z2 that match those in z1, Eric's
> > proposal gives (note the added comma to give a logical indexing
> > vector):
> >
> >> a <- cbind(c(xr1,xs1),c(xr2,xs2))
> >> a[duplicated(a),]
> >       [,1] [,2]
> > [1,]    1    4
> > [2,]    6    7
> >
> > This is obviously wrong, as it gives duplicates *within* z1 and z2,
> > not between them. To get rows of z2 that appear as duplicates of rows
> > of z1, then something like the following should do:
> >
> >> a <- rbind(unique(z1),unique(z2))
> >> a
> >       xr1 xr2
> > [1,]   1   4
> > [2,]   2   5
> > [3,]   6   7
> >> a[duplicated(a),]
> >       xr1 xr2
> > ## nothing
> >
> > I leave it to Erin to determine whether this is relevant to her
> > problem and, if so, how to fix up my suggestion appropriately.
> >
> > Cheers,
> > Bert Gunter
> >
> > "The trouble with having an open mind is that people keep coming along
> > and sticking things into it."
> > -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
> >
> > On Thu, Dec 16, 2021 at 12:39 PM Eric Berger <ericjberger using gmail.com>
> wrote:
> >>
> >>> a <- cbind(c(xr1,xs1),c(xr2,xs2))
> >>> a[duplicated(a)]
> >> [1] 4 4
> >>
> >>
> >> On Thu, Dec 16, 2021 at 10:18 PM Erin Hodgess <erinm.hodgess using gmail.com>
> wrote:
> >>>
> >>> Hello!
> >>>
> >>> I have the following:
> >>>
> >>>   cbind(xr1,xr2)
> >>>
> >>>        xr1 xr2
> >>>
> >>>   [1,]   8   0
> >>>
> >>>   [2,]   7   1
> >>>
> >>>   [3,]   6   2
> >>>
> >>>   [4,]   5   3
> >>>
> >>>   [5,]   4   4
> >>>
> >>>   [6,]   3   5
> >>>
> >>>   [7,]   2   6
> >>>
> >>>   [8,]   1   7
> >>>
> >>>   [9,]   0   8
> >>>
> >>>> cbind(xs1,xs2)
> >>>
> >>>       xs1 xs2
> >>>
> >>> [1,]   9   4
> >>>
> >>> [2,]   8   4
> >>>
> >>> [3,]   7   4
> >>>
> >>> [4,]   6   4
> >>>
> >>> [5,]   5   4
> >>>
> >>> [6,]   4   4
> >>>
> >>> [7,]   3   4
> >>>
> >>>>
> >>>
> >>> These are ordered pairs.  I would like to get something that shows
> that the
> >>> pair (4,4) appears in both.  I have tried cbind with match and %in% and
> >>> intersect, but not getting the exact results.
> >>>
> >>> Any suggestions would be appreciated.  I have a feeling that it's
> something
> >>> really easy that I'm just not seeing.
> >>>
> >>> Thanks,
> >>> Erin
> >>>
> >>>
> >>> Erin Hodgess, PhD
> >>> mailto: erinm.hodgess using gmail.com
> >>>
> >>>          [[alternative HTML version deleted]]
> >>>
> >>> ______________________________________________
> >>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >>> https://stat.ethz.ch/mailman/listinfo/r-help
> http://www.R-project.org/posting-guide.html
> >>> and provide commented, minimal, self-contained, reproducible code.
> >>
> >> ______________________________________________
> >> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >> https://stat.ethz.ch/mailman/listinfo/r-help
> http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
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