[GRASS-user] Definition of Category for Vectors
markus.metz.giswork at googlemail.com
Mon Jan 11 14:39:22 EST 2010
Pedro Roma wrote:
> Hi guys
> I've been reading Neteler/Mitasova book and I have a question:
> Regarding vector data, what is a category?
A category specifies the category a vector feature belongs to, e.g.
highway, major road, minor road for lines or land cover type for areas.
> and Why do I need to have category readers/writters?
In order to change categories of features.
> Because, for What I understood, a category is like a Feature ID that
> links a geometry to its attributes in a DB. Is this correct?
Yes. Also note that one feature can have several categories and several
features can share the same category. A link to attributes in a DB is
optional. An example for classified (categorized) vector features
without a db link is given in
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