[R] Question on Merge/Lookup

Dennis Murphy
Sat, 23 Jan 2010 01:12:33 -0000

sqldf, authored by Gabor, if I read your intention correctly.

D.

On Fri, Jan 22, 2010 at 5:00 PM, Don MacQueen <macq@llnl.gov> wrote:

> Perhaps using the R merge() function, possibly twice in succession, will do
> the job. (merge() does a one to many relational join, but with only two
> dataframes at at time).
>
> Or, there is an R package that lets you use the SQL language on dataframes.
> I don't recall its name, but a search on R packages should turn it up
-- if
> someone else doesn't provide the name sooner.
>
> -Don
>
>
> At 10:52 AM -0800 1/22/10, GL wrote:
>
>> I need to merge three datasets and don't know how. If I were using
SQL, I
>> would use df3, look up the characteristics of each date in df1 and the
>> value
>> for each observation in df2.
>>
>>
>> df1 - unique list of Dates and characteristics of those dates
>> Date, YYYYMM, YYYYWW, DOW
>>
>>
>> df2 - the raw data
>> Date, Place, Value
>>
>>
>> df3 - all posibile combinations of Date + Place (via
>> expand.grid(unique(df2$Date),unique(df2$Place))
>> Date, Place
>>
>> I need to end up with:
>>
>> Date, YYYYMM, YYYYWW, DOW, PLace, Value (plug 0 if combo doesn't
exist in
>> raw data).
>>
>> Appreciate any help!
>>
>>
>> --
>> View this message in context: http://*
>> n4.nabble.com/Question-on-Merge-Lookup-tp1112384p1112384.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
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>>
>
>
> --
> --------------------------------------
> Don MacQueen
> Environmental Protection Department
> Lawrence Livermore National Laboratory
> Livermore, CA, USA
> 925-423-1062
>
>
> ______________________________________________
> R-help@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.
>

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