[GRASS-user] grass vector model, cats and layers concept

[Moritz Lennert]

On 22/04/13 14:41, Vincent Bain wrote:
> Thank you Moritz,
>
>> - I'm not sure I like the difference in size of cat values between
>> layers. It gives the idea that there is one important and two secondary
>> layers.
>
> Sorry, I don't understand. Cats values are all the same font size in the
> drawing (I turned "1" values to sth else, perhaps an optical illusion)

Sorry, I was confused by your "id". I'm not sure that this id is helpful 
in your drawing as most users will never be confronted to id's, only to 
cat values. I think making them this prominent in the drawing might 
cause more confusion than help in understanding.

>
>>
>> - Your attribute table examples all show the classical GRASS usage of
>> category values as indicators of type (type of path, type of plot).
>> Maybe, just to make that point clear, you could use a table with
>> individual cat values for each feature and a second column with type.
>
> You mean showing that "cat" is nothing but a key column, not necessarily
> refering to whatever values in an /exotic/ source of data ?
> +
> I changed column name "cat" to "type" for layer 2

No, what I meant is to have a unique cat for each plot in layer 2 and 
then have an attibute table with columns cat and type, the second then 
giving the type of the plot, while the first is a unique identifier of 
each plot.

Moritz