1v.dissolve(1)                 Grass User's Manual                v.dissolve(1)
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NAME

6       v.dissolve   -  Dissolves  boundaries  between adjacent areas sharing a
7       common category number or attribute.
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KEYWORDS

10       vector, dissolve, area, line
11

SYNOPSIS

13       v.dissolve
14       v.dissolve --help
15       v.dissolve  input=name   [layer=string]    [column=name]    output=name
16       [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]
17
18   Flags:
19       --overwrite
20           Allow output files to overwrite existing files
21
22       --help
23           Print usage summary
24
25       --verbose
26           Verbose module output
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28       --quiet
29           Quiet module output
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31       --ui
32           Force launching GUI dialog
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34   Parameters:
35       input=name [required]
36           Name of input vector map
37           Or data source for direct OGR access
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39       layer=string
40           Layer number or name.
41           Vector  features can have category values in different layers. This
42           number determines which layer to use. When  used  with  direct  OGR
43           access this is the layer name.
44           Default: 1
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46       column=name
47           Name of attribute column used to dissolve common boundaries
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49       output=name [required]
50           Name for output vector map
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DESCRIPTION

53       The  v.dissolve  module is used to merge adjacent areas in a vector map
54       which share the same  category  value.  The  resulting  merged  area(s)
55       retains  this category value. Alternatively an integer or string column
56       can be defined which is used to find adjacent polygons  with  identical
57       attribute  for  common boundary dissolving. In this case the categories
58       are not retained, only the values  of  the  new  key  column.  See  the
59       v.reclass help page for details.
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NOTES

62       GRASS  defines a vector area as composite entity consisting of a set of
63       closed boundaries and a centroid. The centroids must contain a category
64       number  (see v.centroids), this number is linked to area attributes and
65       database links.
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67       Multiple attributes may be linked to a  single  vector  entity  through
68       numbered  fields  referred  to  as layers. Refer to v.category for more
69       details.
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71       Merging of areas can also be accomplished using v.extract -d which pro‐
72       vides  some  additional  options.   In  fact,  v.dissolve  is  simply a
73       front-end to that module. The use of the column parameter adds  a  call
74       to v.reclass before.
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EXAMPLES

77   Basic use
78       v.dissolve input=undissolved output=dissolved
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80   Dissolving based on column attributes
81       North Carolina data set:
82       g.copy vect=soils_general,mysoils_general
83       v.dissolve mysoils_general output=mysoils_general_families column=GSL_NAME
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85   Dissolving adjacent SHAPE files to remove tile boundaries
86       If tile boundaries of adjacent maps (e.g. CORINE Landcover SHAPE files)
87       have to be removed, an extra step  is  required  to  remove  duplicated
88       boundaries:
89       # patch tiles after import:
90       v.patch -e `g.list type=vector pat="clc2000_*" separator=","` out=clc2000_patched
91       # remove duplicated tile boundaries:
92       v.clean clc2000_patched out=clc2000_clean tool=snap,break,rmdupl thresh=.01
93       # dissolve based on column attributes:
94       v.dissolve input=clc2000_clean output=clc2000_final col=CODE_00
95

SEE ALSO

97        v.category, v.centroids, v.extract, v.reclass
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AUTHORS

100       module:  M.  Hamish Bowman, Dept. Marine Science, Otago University, New
101       Zealand
102       Markus Neteler for column support
103       help page: Trevor Wiens
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SOURCE CODE

106       Available at: v.dissolve source code (history)
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108       Main index | Vector index | Topics index | Keywords index  |  Graphical
109       index | Full index
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111       © 2003-2019 GRASS Development Team, GRASS GIS 7.8.2 Reference Manual
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115GRASS 7.8.2                                                      v.dissolve(1)
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