NAME

       v.category  - Attach, delete or report vector categories to map geometry.

KEYWORDS

       vector, category

SYNOPSIS

       v.category
       v.category help
       v.category  [-g]  input=name  [output=name]   [option=string]   [type=string[,string,...]]
       [layer=integer[,integer,...]]       [ids=range]        [cat=integer]        [step=integer]
       [--overwrite]  [--verbose]  [--quiet]

   Flags:
       -g
           Shell script style, currently only for report
           Format: layer type count min max

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name
           Name of input vector map

       output=name
           Name for output vector map

       option=string
           Action to be done
           Options: add,del,chlayer,sum,report,print,layers
           Default: add
           add: add a new category
           del: delete all categories of given layer
           chlayer: change layer number (e.g. layer=3,1 changes layer 3 to layer 1)
           sum: add the value specified by cat option to the current category value
           report: print report (statistics), in shell style: layer type count min max
           print: print category values, more cats in the same layer are separated by '/'
           layers: print only layer numbers

       type=string[,string,...]
           Feature type
           Options: point,line,boundary,centroid,area
           Default: point,line,boundary,centroid,area

       layer=integer[,integer,...]
           Layer number
           A  single  vector  map  can  be  connected  to  multiple  database tables. This number
           determines which table to use.
           Default: 1

       ids=range
           Feature ids (by default all features are processed)
           Example: 1,3,7-9,13

       cat=integer
           Category value
           Default: 1

       step=integer
           Category increment
           Default: 1

DESCRIPTION

       v.category  attaches,  deletes  or  reports  vector  categories  to  map  geometry.  These
       categories  (IDs) are used to link geometry object(s) to attribute records (from attribute
       table linked to vector map).

NOTES

       Use v.to.db to upload related categories to a linked attribute table.

       The type parameter specifies the type of geometry objects to which the category is  added;
       it is similar to an input filter - only the geometry specified in 'type' is processed.

       If  the  type  parameter  is  set  to  centroid  and  the option parameter set to add, new
       categories will be added to existing centroids. Note however, that new centroids cannot be
       created  this  way.   To  do  so,  they must be added manually using v.digit or by running
       v.category with the type parameter set to area.

       Areas are a special case because it is impossible to attach a cat to  an  area  without  a
       centroid; in this case, the module places new centroids in areas automatically.

       The cat parameter is only used with option=add and option=sum.

       The  ids  parameter specifies the list of feature IDs to which the operation is performed;
       by default, all vector feature ids are processed.  The feature ID is an internal  (unique)
       geometry  ID  that  all  vector  primitives possess, and is separate from any category the
       feature may also possess.
         v.edit map=inputname tool=select
        to find out the geometry ids of certain features.

EXAMPLES

   Report vector categories

       v.category input=testmap option=report
       LAYER/TABLE 1/testmap:
       type       count        min        max
       point          0          0          0
       line        1379          1       1379
       boundary       0          0          0
       centroid       0          0          0
       area           0          0          0
       all         1379          1       1379

   Delete all vector categories in layer 1

       v.category input=testmap output=outmap option=del

   Add vector categories in layer 1 with step=2

       v.category input=outmap output=stepmap option=add step=2
       # report
       v.category input=stepmap option=report
       LAYER/TABLE 1/outmap:
       type       count        min        max
       point          0          0          0
       line        1379          1       2757
       boundary       0          0          0
       centroid       0          0          0
       area           0          0          0
       all         1379          1       2757

   Add categories/centroids to a vector map without categories

       v.category input=wkt output=wktnew option=add
        Results can be tested using d.what.vect.

   Print vector categories of given layer
       Print vector categories from the first layer, only for feature ids 1-50.
       v.category input=roads option=print layer=1 id=1-50

SEE ALSO

        v.centroids, v.db.connect, v.edit, v.to.db

AUTHOR

       Radim Blazek, ITC-irst, Trento, Italy
       Modified (the id parameter) by Martin Landa, FBK-irst (formerly ITC-irst), Trento,  Italy,
       2008/02

       Last changed: $Date: 2011-11-08 01:42:51 -0800 (Tue, 08 Nov 2011) $

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