[R] Dataframe by Serial ID

[Eric Berger]

Hi Thomas,
Jeff is correct that this can be handled via merge, e.g.
df3 <- merge( df2, df1, by="Serial", all=FALSE )

This operation is called an "inner join", and you could use other tools,
such as the dplyr package to accomplish the same thing

df3 <- dplyr::inner_join( df2, df1, by="Serial" )

HTH,
Eric


On Wed, Jan 8, 2020 at 5:05 PM Jeff Newmiller <jdnewmil using dcn.davis.ca.us>
wrote:

> "merge" is generally the base R answer to this question, and there are
> equivalent functions in various contributed packages.
>
> However, it is necessary to identify which columns in each table uniquely
> identify each row ("primary key"). If your Serial 3036 shows up 10 times in
> the first table and 10 times in the second table then you will end up with
> all combinations of those rows (100 rows) in a merge that uses only Serial
> to match rows. Is that what you want?
>
>
> On January 8, 2020 6:52:18 AM PST, Thomas Subia <tsubia using imgprecision.com>
> wrote:
> >Colleagues,
> >
> >I have two data frames which look like this.
> >
> >Data frame 1
> >
> >       Serial  Pre.Hole        Pre.flow        Pre.Date
> >1      3036        1                   0.24            19-Nov-19
> >2      3036        2                   0.212           19-Nov-19
> >3      3036        3                   1.292           19-Nov-19
> >4      3036        4                   0.262           19-Nov-19
> >5      3036        5                   1.291           19-Nov-19
> >6      3036        6                   0.26            19-Nov-19
> >
> >Data frame 2
> >
> >       Serial   Post.Hole      Post.flow       Post.Date
> >62323  11024        44                 -0.678          11-Dec-19
> >62324  11024        45                 -0.659          11-Dec-19
> >62325  11024        46                  -0.654                 11-Dec-19
> >62326  11024        47                 -0.699          11-Dec-19
> >62327  11024        48                  -0.671                 11-Dec-19
> >62328  11024        49                 -0.687          11-Dec-19
> >
> >What I want is to create a data frame whose serials numbers are common
> >to data frames 1 and 2.
> >The resulting data frame 1st row would look like this.
> >
> >Serial         Post.Hole       Post.flow       Post.Date       Pre.Hole
>       Pre.flow        Pre.Date
> >
> >Any ideas on how to do this would be appreciated.
> >
> >Thomas Subia
> >Statistician / Senior Quality Engineer
> >
> >IMG Companies
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> >
> >
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