[R] person-level to person-period xfm

[Robert Terwilliger]

Dear R experts,

I have a so-called person-level data frame that I need to transform
into a person-period data frame.

If the lingo is unclear, the data have one row for each subject, with
repeated measures data each in a separate column.

I need to transform these data so that each subject has multiple rows,
one for each repeated measure value.

Is there a quick-and-dirty way to do this transformation?

Many thanks,

-- 
Robert Terwilliger
Biomedical Physicist
Laboratory of Neurocognitive Development
Western Psychiatric Institute and Clinic
University of Pittsburgh Medical Center
Loeffler Building
121 Meyran Avenue  #114
Pittsburgh, PA 15213
412.383.8174  - Office
412.383.8179 - Fax
em: raterwil at gmail.com
http://www.wpic.pitt.edu/research/lncd/