[R] problems with merge() - the output has many repeated lines

[Erik Iverson]

Cecilia -

Find what columns you're matching on,

intersect(names(df1), names(df2)),

Maybe that will shed some light on the issue.

On 08/22/2010 12:02 PM, Cecilia Carmo wrote:
> Thanks, but I don't have multiple matches and the lines repeated in the
> final dataframe are exactly equal in all columns.
>
> Cecília
>
> Sat, 21 Aug 2010 10:58:53 -0500
> Hadley Wickham <hadley at rice.edu> escreveu:
>> You may find a close reading of ?merge helpful, particularly this
>> sentence: "If there is more than one match, all possible
>> matches contribute one row each" (so check that you don't have
>> multiple matches).
>>
>> Hadley
>>
>> On Sat, Aug 21, 2010 at 10:45 AM, Cecilia Carmo <cecilia.carmo at ua.pt>
>> wrote:
>>> Hi everyone,
>>>
>>> I have been merging many big dataframes (about 80000 rows each) and I
>>> never
>>> had this problem, but now it happened to me and I want to know if
>>> someone
>>> knows what could be happening.
>>> The final dataframe has many rows, an impossible number! I have done
>>> edit(dataframe) and I saw that there are many repeated rows (all equal).
>>>
>>> Thanks for any help,
>>>
>>> Cecília Carmo
>>> Universidade de Aveiro
>>> Portugal
>>>
>>> ______________________________________________
>>> R-help at 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.
>>>
>>
>>
>>
>> --
>> Assistant Professor / Dobelman Family Junior Chair
>> Department of Statistics / Rice University
>> http://had.co.nz/
>
> ______________________________________________
> R-help at 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.