R help - Jan 2009 - Creating list or numeric vectors out of selected columns of row oriented data

I am just assuming this can be done, but I have not gotten close to  
making it happen. I have a data file with about 1 million rows with  
1470 unique subjects. Each row represents a small set of observations  
made on a specific date for a single subject. I would like to  
transform the data so that I have an R object with a single entry for  
each subject and start date and vectors for the observation dates and  
the observations. The data are something like the following where for  
each subject the subject_id does not change and the start_date does  
not change, but the obeservation_date and the three different  
observations change between rows. (There is one row for each day for  
each subject over a three year period although some entered the study  
late):
'subject_id',
'start_date','observation_date','weight_obs',
'activity_obs','calories_obs'
1,'1/1/2005','1/1/2005',3.26,'a',93
1,'1/1/2005','1/2/2005',3.22,'o',85
1,'1/1/2005','1/3/2005',3.28,'o',91
...
1,'1/1/2005','12/31/2008',4.38,'h',102
2,'2/13/2005','2/13/2005',3.02,'l',80
2,'2/13/2005','2/14/2005',3.08,'j',85
...

Any guidance is appreciated.

R. Mark Sharp, Ph.D.
Director of Primate Records Database
Southwest National Primate Center
Southwest Foundation for
	Biomedical Research
P.O. Box 760549
San Antonio, TX 78245-0549
Telephone: (210)258-9476
e-mail: msharp@sfbr.org




	[[alternative HTML version deleted]]

Yes the data can probably be easily transformed, but you would have to
provide an example of what the input looks like to understand what has
to be done with the data and how variable it might be so we can
understand how we might have to "parse" the data from the input.  Are
the missing days supposed to be filled with with NAs?

On Tue, Jan 27, 2009 at 10:36 AM, R. Mark Sharp <msharp at sfbr.org>
wrote:
> I am just assuming this can be done, but I have not gotten close to
> making it happen. I have a data file with about 1 million rows with
> 1470 unique subjects. Each row represents a small set of observations
> made on a specific date for a single subject. I would like to
> transform the data so that I have an R object with a single entry for
> each subject and start date and vectors for the observation dates and
> the observations. The data are something like the following where for
> each subject the subject_id does not change and the start_date does
> not change, but the obeservation_date and the three different
> observations change between rows. (There is one row for each day for
> each subject over a three year period although some entered the study
> late):
> 'subject_id',
'start_date','observation_date','weight_obs',
> 'activity_obs','calories_obs'
> 1,'1/1/2005','1/1/2005',3.26,'a',93
> 1,'1/1/2005','1/2/2005',3.22,'o',85
> 1,'1/1/2005','1/3/2005',3.28,'o',91
> ...
> 1,'1/1/2005','12/31/2008',4.38,'h',102
> 2,'2/13/2005','2/13/2005',3.02,'l',80
> 2,'2/13/2005','2/14/2005',3.08,'j',85
> ...
>
> Any guidance is appreciated.
>
> R. Mark Sharp, Ph.D.
> Director of Primate Records Database
> Southwest National Primate Center
> Southwest Foundation for
>        Biomedical Research
> P.O. Box 760549
> San Antonio, TX 78245-0549
> Telephone: (210)258-9476
> e-mail: msharp at sfbr.org
>
>
>
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
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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.
>


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

What is the problem that you are trying to solve?