NAME

       v.patch  - Creates a new vector map by combining other vector maps.

KEYWORDS

       vector, geometry, level1

SYNOPSIS

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

   Flags:
       -n
           Do not expect input with topology
           Applicable when input is points without topology

       -z
           Expect z coordinate even when not using topology
           Applicable when input is points with z coordinate but without topology

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

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

       -b
           Do not build topology
           Advantageous when handling a large number of points

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       input=name[,name,...] [required]
           Name of input vector map(s)
           Or data source(s) for direct OGR access

       output=name [required]
           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 -e flag, v.patch shifts category (cat) values in the output so that category numbers  from
       the  different  input  maps  do  not  overlap.  This  shift is applied to both the category values of the
       features and the category values in the attribute tables. Hence, there is no need to run  v.category  and
       v.db.update beforehand.

       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

SOURCE CODE

       Available at: v.patch source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual