[GRASS-user] RE: Problem querying layers other than '1' in gis.m

[Moritz Lennert]

Immediately replying to myself to correct an error in my explanation:

On Tue, September 19, 2006 23:51, Moritz Lennert wrote:
> On Tue, September 19, 2006 21:34, Patton, Eric wrote:
>> I'm having trouble querying layer two on my vector map in gis.m. I can
>> query both the columns and data of layer one without problems. Maybe I
>> misunderstand the use of the tool. Are we supposed to be able to query
>> multiple layers on gis.m? If not, disregard the following. If so, read
>> on.

[...]

> Are you sure that you are using the layers correctly ? I've that the same
> head scratching which lead to this thread:
> http://grass.itc.it/pipermail/grass5/2005-September/019592.html
>
> The way I understand it, you cannot link the same features to two
> different tables. You would have to duplicate your points from layer 1 to
> layer 2 to be able to link them to another table.

You do not have to duplicate the points, but IIUC you have to assign a
category value for each point in each layer. (See
http://mpa.itc.it/markus/grass63progman/Vector_Library.html#vlib_categories_layers)


BTW: have you tried to query on the command line (using d.mon x0 to open a
monitor) ?

Moritz