How do you extend factor() without abstract data types?
The idea is to have
factor (x, TYPE)
to transform all or selected components of x to factor TYPE.
Value:
a data structure of same type as x, with factor-like components
transformed to be like TYPE.
In the Pascal family, you would define an abstract data type. In R, the
best seems to be to provide a prototype example.
This should be fail-save, and maybe a candidate to extend the base
factor() function.
A draft that can handle a very limited range of cases is in
<http:///sintro.r-forge.r-project.org/sprof/asfactormodel.R>
and documented in
<http:///sintro.r-forge.r-project.org/sprof/sprof_internal.pdf>.
Comments and recommendations are welcome.
gs.
--
G. Sawitzki
StatLab Heidelberg
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