[R] Merging Data Sets with Full Outer Join

[David Winsemius]

> On Apr 19, 2016, at 11:23 PM, G.Maubach at weinwolf.de wrote:
> 
> Hi All,
> 
> I would like to match some datasets. Both deliver variables AND cases 
> which might or might not be present in all datasets:
> 
> This sequence
> 
> Kunden <- Kunden_2011 
> Kunden <- merge(Kunden, Kunden_2012,
>                by.x = "Debitor", by.y = "Debitor")
> 
> Kunden <- merge(Kunden, Kunden_2013,
>                by.x = "Debitor", by.y = "Debitor")
> 
> Kunden <- merge(Kunden, Kunden_2014,
>                by.x = "Debitor", by.y = "Debitor")
> 
> Kunden <- merge(Kunden, Kunden_2015,
>                by.x = "Debitor", by.y = "Debitor")
> 
> delivers too few cases. So I guess it does an equi-join.

You should not be guessing. Read the help page. It calls the default setting a natural join.

> 
> How can I join the datasets and keep the variables as well as the cases?
> 

If you want a full outer join use all=TRUE. This, too, should have been in the ?merge help page.


> I am looking forward to your reply.
> 
> Kind regards
> 
> Georg
> 
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David Winsemius
Alameda, CA, USA