[R] Merging two data set in R,

Sarah Goslee sarah.goslee at gmail.com
Wed Aug 25 14:08:23 CEST 2010

What do you want to happen when there are duplicates?

1  a
2  b
3  c

1  x
2  y
2  z

What happens to ID 1? 2? 3? in your desired output?

The all.x and all.y options might be of use.


On Wed, Aug 25, 2010 at 8:00 AM, Mangalani Peter Makananisa
<pmakananisa at sars.gov.za> wrote:
> I want to merge data set A and B, by merge(A,B, by = "ID"), however I am getting  error massages, because the some ID's in A repeat themselves several time in data set B. Even if the ID's in B repeat themselves I want to be able to merge the two dataset and retrieve the intersection.
> Please help.
> -----Original Message-----
> From: Sarah Goslee [mailto:sarah.goslee at gmail.com]
> Sent: 25 August 2010 01:52 PM
> To: Mangalani Peter Makananisa
> Cc: r-help at r-project.org
> Subject: Re: [R] Merging two data set in R,
> First you need to clarify what you'd like to happen when the ID in B
> is not unique. What do you want the resulting dataframe to look
> like?
> Some possible answers involve using different options for merge() or
> using unique() to remove duplicates from B before merging. But
> at least to me, "merge or retrieve the common ones" isn't clear
> enough to be able to say which.
> Sarah
> On Wed, Aug 25, 2010 at 5:35 AM, Mangalani Peter Makananisa
> <pmakananisa at sars.gov.za> wrote:
>> Dear R Gurus,
>> I am currently working on the two dataset ( A and B), they both have the
>> same fields:    ID , REGION, OFFICE, CSTART, CEND, NCYCLE, STATUS and
>> CB.
>> I want to merge the two data set by ID. The problem I have is that the
>> in data A, the ID's are unique. However in the data set B, the ID's are
>> not unique, thus some repeat themselves.
>> How do I the merge or retrieve the common ones?
>> Please advise.
>> Kind Regards
>> Peter

Sarah Goslee

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