[GRASS-user] v.dissolve bugfeature / workaround needed
Milton Cezar Ribeiro
miltinho.astronauta at gmail.com
Wed Aug 6 12:40:35 EDT 2008
Following Morit´z suggestion, how about you use R on this task?
#The code below is to you read your dbf file
#so remove the # and include your full path/file name
#below we simulate a data.frame (it is a table)
#below you have a code to "deparse" your variable of interest
2008/8/6, Moritz Lennert <mlennert at club.worldonline.be>:
> On 06/08/08 15:09, peter.loewe at gmx.de wrote:
>> 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 -
> v.dissolve is only a frontend script to v.reclass which needs ints...
> 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) ?
> If you absolutely need to work with the dbf-driver, then I guess you best
> bet would be to open the dbf file in OpenOffice Calc and use its functions.
> If you can switch over to SQLite, I think the ltrim function should do what
> you need.
> More full-fledged SQL-backends obviously have more sophisticated functions.
> grass-user mailing list
> grass-user at lists.osgeo.org
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