[R] aggregate text column by a few rows

[Tan, Richard]

Thank you!
Richard


-----Original Message-----
From: jim holtman [mailto:jholtman at gmail.com] 
Sent: Thursday, October 07, 2010 12:08 PM
To: Tan, Richard
Cc: r-help at r-project.org
Subject: Re: [R] aggregate text column by a few rows

try this using sqldf:

> a
  id name   hobby
1  1  Tom fishing
2  1  Tom reading
3  2 Mary reading
4  3 John boating
5  2 Mary running
> require(sqldf)
> sqldf('select name, group_concat(hobby) hobby from a group by id', method='raw')
  name           hobby
1  Tom fishing,reading
2 Mary reading,running
3 John         boating


On Thu, Oct 7, 2010 at 11:52 AM, Tan, Richard <RTan at panagora.com> wrote:
> Hi, R function aggregate can only take summary stats functions, can I
> aggregate text columns?  For example, for the dataframe below,
>
>
>
>> a <- rbind(data.frame(id=1, name='Tom',
> hobby='fishing'),data.frame(id=1, name='Tom',
> hobby='reading'),data.frame(id=2, name='Mary',
> hobby='reading'),data.frame(id=3, name='John',
> hobby='boating'),data.frame(id=2, name='Mary', hobby='running'))
>
>> a
>
>  id name   hobby
>
> 1  1  Tom fishing
>
> 2  1  Tom reading
>
> 3  2 Mary reading
>
> 4  3 John boating
>
> 5  2 Mary running
>
>
>
>
>
> I want output as
>
>>b
>
> id name hobbies
>
> 1 Tom    fishing reading
>
> 2 Mary reading running
>
> 3 John boating
>
>
>
>
>
>
>
> Thanks,
>
> Richard
>
>
>
>
>        [[alternative HTML version deleted]]
>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

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