[R] data manipulation

[Thomas Lumley]

This is what reshape() does.

 	-thomas

On Thu, 8 Sep 2005, Marc Bernard wrote:

> Dear All,
>
> I would be grateful if you can help me. My problem is the following:
> I have a data set like:
>
> ID  time      X1          X2
> 1    1          x111      x211
> 1    2          x112      x212
> 2    1          x121      x221
> 2    2          x122      x222
> 2    3          x123      x223
>
> where X1 and X2 are 2 covariates and "time" is the time of observation and ID indicates the cluster.
>
> I want to merge the above data by creating a new variable  "X" and "type" as follows:
>
> ID   time    X            type
> 1     1      x111         X1
> 1     2      x112         X1
> 1     1      x211         X2
> 1     2      x212         X2
> 2     1      x121         X1
> 2     2      x122         X1
> 2     3      x123         X1
> 2     1      x221         X2
> 2     2      x222         X2
> 2     3      x223         X2
>
>
> Where "type" is a factor variable indicating if the observation is related to X1 or X2...
>
> Many thanks in advance,
>
> Bernard
>
>
> ---------------------------------
>
>
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Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle