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

[Milton Cezar Ribeiro]

Hi Peter,

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
#require(foreign)
#my.dbf<-read.dbf("c:/temp/myfile.dbf") #


#below we simulate a data.frame (it is a table)

my.dbf<-data.frame(cbind(var1=c("GRASS001","GRASS002","GRASS003")))
my.dbf

#below you have a code to "deparse" your variable of interest

my.dbf$var2_char<-substr(my.dbf$var1,6,999)
my.dbf

my.dbf$var2_int <-as.numeric(as.character(my.dbf$var2_char))
my.dbf



Cheers,



miltinho

brazil




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.
>>
>
> +1
>
>
>> 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.
>
> Moritz
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20080806/89c5e142/attachment.html