Or:
> data.frame( hobs= tapply(a$hobby, list( a$name), c))
hobs
Tom fishing, reading
Mary reading, running
John boating
Note Jim's gives you the names as columns while this has them as
rownames. Further differences : my version has the column as lists
whereas Jim's returns them as concatenated strings. Each result may
have it advantages depending on your applications.
> dfrm[1,1][[1]][1]
[1] "fishing"
> "fishing" %in% dfrm[1,1][[1]]
[1] TRUE
With Jim's you could not individually access the hobby items:
> dfrm2[1,2]
[1] "fishing,reading"
# But you could "grep" them
> grepl("fishing" , dfrm2[1,2])
[1] TRUE
--
David
On Oct 7, 2010, at 12:08 PM, jim holtman wrote:
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 <r...@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
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--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem that you are trying to solve?
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
