[GRASSLIST:6129] Re: dissolve common boundary

[Moritz Lennert]

On Fri, March 11, 2005 12:49, ivan marchesini said:
> Dear all...
> I try to answer all your questions and remarks...
>
> -The areas are obtained from overlay operations and are perfectly
> overlapping (also zooming in....)
>
> - I have tried to search the "column" option in v.category, but I didn't
> find it
>

v.reclass, not v.category


> - I didn't understand how the new parameter works... if I put new=1 the
> table is not created... and if I put new=1 the original category are
> mantained (boundary not dissolved)... which value is better???
>
> how can I solve the problem???
>
> thank you very much...
>
> ivan
>
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> Il giorno ven, 11-03-2005 alle 10:28 +0100, Moritz Lennert ha scritto:
>> On Thu, March 10, 2005 19:56, ivan marchesini said:
>> > Dear Hamish, dear Markus...
>> > I have still problem to dissolve boundaries...
>> > I will try to explain better the problem...
>> > I have a lot of areas (a reclassified landuse map) in a vector map...
>> > some of these poligon have the same values in a column of the
>> > database...
>> > for example: two touching areas have the same code=31
>> > I would like that these two ares will became one single area .... and
>> > the same for the other touching areas which have equal code values....
>> >
>> > I have tried
>> > v.extract -d input=landuse output=landuse_diss type=area new=-1
>> >
>> >
>> > but the output is exactly the same map as the input
>> >
>> > where I'm wrong???
>> > can you help me??
>>
>> It dissolves, if the category values are equal, not any value in the
>> attribute
>> table. So, you will first have to use v.reclass with the 'column' option to
>> take new category values from the desired column and then v.extract -d on
>> the
>> resulting map.
>>
>> Moritz
>>
> --
> Ivan Marchesini
> Department of Civil and Environmental Engineering
> University of Perugia
> Via G. Duranti 93/a
> 06125
> Perugia (Italy)
> e-mail: marchesini at unipg.it
>         ivan.marchesini at gmail.com
> tel: +39(0)755853760
> fax: +39(0)755853756
>
>
>
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