[GRASS-user] [GRASS-dev] v.dissolve confusion

[Vaclav Petras]

Hi Michael,

On Fri, 15 Mar 2024 at 20:00, Michael Barton via grass-dev <
grass-dev at lists.osgeo.org> wrote:

> Any suggestions about what is wrong with either of the versions of this
> dissolve command?
>
> v.dissolve --overwrite input=alcala_subsectors at SAA2024 column=ID
> output=alcala_subsectors_dissolved at SAA2024
> aggregate_columns=group_concat(REGION),max(STRATUM),max(SECTOR),avg(SUBSECTOR),group_concat(SECTOR_ID),sum(AREA),group_concat(SURVEYED),avg(IDNUM)
> result_columns="region TEXT,stratum INTEGER,sector INTEGER,subsector
> REAL,sector_ID TEXT,area REAL,surveyed TEXT,IDnum REAL"
>

What I can say based on this command is that the equivalent command from
the manual page for NC SPM sample dataset works both in terminal and GUI
(and a similar one runs through Python in CI). So, a minimal reproducible
example would be needed.


> In both cases, I get the error:
> Option <result_columns> requires all of <aggregate_columns>
>

However, perhaps this will help: This message comes from the command line
parser. This means that the parameter validation fails even before this
hits any of the code specific for v.dissolve. This is the parser simply
reading and enforcing the line "requires_all:
result_columns,aggregate_columns" which says if result_columns is provided,
aggregate_columns must be provided too. Given that the parser does not go
beyond checking the presence of parameters here, it is highly unlikely that
specific data would trigger an issue. So, maybe double check your inputs
before creating a minimal reproducible example.

Best,
Vaclav
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