[GRASS-user] v.dissolve bugfeature / workaround needed

peter.loewe at gmx.de peter.loewe at gmx.de
Wed Aug 6 09:09:57 EDT 2008

Hello list,

i am using GRASS 6.4svn to merge adjacent poylgons into larger units. The merging is controlled by a column of type CHAR:

v.dissolve input=counties output=counties_merged_fips1 column=FIPS_1 

results in
dbmi: Protocol error
ERROR: Cannot open select cursor: SELECT cat, FIPS_1 FROM counties
       ORDER BY FIPS_1
ERROR: Unable to open vector map <counties_fips1_22157 at admin_borders>
       on topology level 2
WARNING: Table <counties_fips1_22157> linked to vector map
         <counties_fips1_22157> does not exist
ERROR: Vector map <counties_fips1> not found in the current mapset

v.dissolve works correctly when applied to an INT column.

I assume this is a bugfeature - string-based dissolving would be great to have at some point.

For now, does anybody have a (DBdriver-)SQL-hack to transmogrify strings like "GRASS001", "GRASS002", "GRASS003" into the Integers 1,2,3 ? (aka getting rid of the "GRASS"-part of the string) ?

Dr. Peter Löwe
<peter.loewe at gmx.de>

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