Hi Simon
Thanks for the clarification - makes sense and I now think youre right -
probably better to avoid an automatic factor conversion and let the user
explicitly convert if necessary. And you are right, I did abuse the term factor
when referring to varchar - instead of factor, I really meant something like
'internalized strings' a la Java (ie like a factor but with no ordering or
distinct levels attributes.
Many thanks
-- Rory
On 27/12/2012, at 5:47 PM, Simon Urbanek <simon.urba...@r-project.org> wrote:
> varchars are character strings. Factors consists of index and level set, so
> if your DB doesn't keep those separate, it is not a factor (and below you
> suggest it doesn't). Even if the DB supports ordered and unordered sets, the
> drivers typically only return the strings anyway, so you don't get at the set
> (without querying the schema). To make a point - a factor is if you can have
> a column consisting of values A,A,B,B and a level set of A,B,C (i.e. C is not
> used so it is extra information that you cannot express in a character
> string). if you don't have levels information nor the order then it's just a
> character vector.
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