R help - Sep 2005 - Transform variable number of rows per subject to column variables?

Hello,

I am very new to R, but I am having trouble with my dataset.

I have a data frame where a subject has a variable number of multiple 
observations for each row, which I wish the transform these 
observations to column variables.

An example of the data frame
ID 	TEST.A	TEST.B
1	10	1
1	13	2
1	11	1
2	15	2
2	17	3

And I wish to transform it to the following:
ID	TEST.A1	TEST.A2	TEST.A3	TEST.B1	TEST.B2	TEST.B3
1	10		13		11		1		2		1
2	15		17		NA		2		3		NA

In other words, for the variable number of repeated follow up 
studies, a new column variable for each subject, but they are grouped 
by the original test.

Thank you for any help - I'm realizing that I am a terrible programmer!

Bing Ho

On 9/20/05, Bing Ho <2bingho at stanford.edu>
wrote:
> Hello,
> 
> I am very new to R, but I am having trouble with my dataset.
> 
> I have a data frame where a subject has a variable number of multiple
> observations for each row, which I wish the transform these
> observations to column variables.
> 
> An example of the data frame
> ID      TEST.A  TEST.B
> 1       10      1
> 1       13      2
> 1       11      1
> 2       15      2
> 2       17      3
> 
> And I wish to transform it to the following:
> ID      TEST.A1 TEST.A2 TEST.A3 TEST.B1 TEST.B2 TEST.B3
> 1       10              13              11              1               2  
1
> 2       15              17              NA              2               3  
NA
> 
> In other words, for the variable number of repeated follow up
> studies, a new column variable for each subject, but they are grouped
> by the original test.

First manufacture a "time" column and then use reshape:

tt <- sequence(rle(DF$ID)$lengths)
reshape(cbind(tt, DF), idvar = "ID", timevar = "tt",
direction = "wide")

Another possibility is to use the reshape package:

library(reshape)
DF.d <- deshape(cbind(tt, DF), id = 1:2)  # same tt as above
reshape(DF.d, ID ~ variable + tt)

Hey Bing,

Reshape's the ticker -- ?reshape.

For example, reshape(myFrame, idvar = "ID", timevar =
"TEST.A") should
do most of the trick.

Kevin

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Bing Ho
Sent: Monday, September 19, 2005 10:04 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Transform variable number of rows per subject to column
variables?

Hello,

I am very new to R, but I am having trouble with my dataset.

I have a data frame where a subject has a variable number of multiple 
observations for each row, which I wish the transform these 
observations to column variables.

An example of the data frame
ID 	TEST.A	TEST.B
1	10	1
1	13	2
1	11	1
2	15	2
2	17	3

And I wish to transform it to the following:
ID	TEST.A1	TEST.A2	TEST.A3	TEST.B1	TEST.B2	TEST.B3
1	10		13		11		1
2		1
2	15		17		NA		2
3		NA

In other words, for the variable number of repeated follow up 
studies, a new column variable for each subject, but they are grouped 
by the original test.

Thank you for any help - I'm realizing that I am a terrible programmer!

Bing Ho

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