NAME

       v.patch  - Create a new vector map layer by combining other vector map layers.

KEYWORDS

       vector, geometry

SYNOPSIS

       v.patch
       v.patch help
       v.patch [-ae] input=name[,name,...] output=name  [bbox=name]   [--overwrite]  [--verbose]  [--quiet]

   Flags:
       -a
           Append files to existing file (overwriting existing files must be activated)

       -e
           Copy also attribute table
           Only the table of layer 1 is currently supported

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=name[,name,...]
           Name of input vector map(s)

       output=name
           Name for output vector map

       bbox=name
           Name for output vector map where bounding boxes of input vector maps are written to

DESCRIPTION

       v.patch allows the user to combine any number of vector maps together to create one composite vector map.
       If the table structures are identical, attributes are transferred to the new table.

NOTES

       Any vectors that are duplicated among the maps being patched together (e.g., border lines) will  have  to
       be edited or removed after v.patch is run. Such editing can be done automatically using v.clean.

       Lines may need to be snapped with v.clean tool=snap,break,rmdupl.

       Boundaries  may  need  to  be  cleaned with v.clean tool=break,rmdupl,rmsa repeatedly until the rmsa tool
       (Remove small angles at nodes) no longer modifies any boundaries. If vector topology is still not  clean,
       boundaries may also need to be snapped with v.clean tool=snap,break,rmdupl.

       When  using  the  -a flag, the user has to make sure that the features in the different maps added to the
       output map do not have overlapping category numbers, unless identical category numbers reflect  identical
       attributes,  otherwise  the  attributes  of  the  added  maps  are  lost. To avoid this, the user can use
       v.category option=sum to change category values of some of the maps before patching.

EXAMPLES

       Patch together two maps with mixed feature types:
          v.patch input=geology,streams out=geol_streams

       Append one map to another:
          g.copy vect=roads,transport
          v.patch -a input=railroads output=transport --overwrite

SEE ALSO

       v.clean, v.build, v.select, v.overlay

AUTHORS

       Dave Gerdes, U.S.Army Construction Engineering Research Laboratory
       Radim Blazek, ITC-Irst, Trento, Italy

       Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $

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