[Rd] A "stack" function

Thomas Lumley thomas@biostat.washington.edu
Wed, 29 Mar 2000 08:16:37 -0800 (PST)

On 29 Mar 2000, Douglas Bates wrote:

> I am using R in my undergraduate engineering statistics courses, in
> which I am currently discussing one-way analysis of variance.  Many of
> the data sets for the exercises or examples give the data in the form
> on one column per treatment level.  To use the aov or lm functions
> such data should be converted to one column with all the response
> observations and a companion column with indicators of the treatment
> level.
> In Minitab this operation is called "stacking" columns and the command
> to perform the operation is "stack".  I have written a similar function
> for R.  Before taking the time to make it elegant and to document it,
> I thought I would check if I have overlooked an existing way of doing
> this.

It would be really nice if you could also do the reverse: take repeated
measurements in 'long' form and convert them into 'wide' form.
  In Stata both of these are available in the -reshape- command.  I don't
know any really simple way of doing it in R.


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