GRASS GIS manual: v.edit

Note: A new GRASS GIS stable version has been released: GRASS GIS 7.8, available here.
Updated manual page: here

NAME

v.edit - Edits a vector map, allows adding, deleting and modifying selected vector features.

KEYWORDS

vector, geometry, editing, line, node, point, vertex, level1

SYNOPSIS

v.edit

v.edit --help

v.edit [-rcnb1p] map=name [layer=string] [type=string[,string,...]] tool=string [input=name] [move=x,y,z] [threshold=float[,float,...]] [ids=range] [cats=range] [coords=x,y[,x,y,...]] [bbox=x1,y1,x2,y2] [polygon=x,y[,x,y,...]] [where=sql_query] [query=string] [bgmap=name[,name,...]] [snap=string] [zbulk=value,step] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-r: Reverse selection
-c: Close added boundaries (using threshold distance)
-n: Do not expect header of input data
-b: Do not build topology; Advantageous when handling a large number of points
-1: Modify only first found feature in bounding box
-p: Connect parallel lines (using extend tools and threshold distance)
--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:

map=name [required]: Name of vector map to edit; Or data source for direct OGR access
layer=string: Layer number or name; Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.; Default: 1
type=string[,string,...]: Input feature type; Options: point, line, boundary, centroid; Default: point,line,boundary,centroid
tool=string [required]: Tool; Options: create, add, delete, copy, move, flip, catadd, catdel, merge, break, snap, connect, extend, extendstart, extendend, chtype, vertexadd, vertexdel, vertexmove, areadel, zbulk, select; create: Create new (empty) vector map; add: Add new features to existing vector map; delete: Delete selected features from vector map; copy: Copy selected features; move: Move selected features in vector map; flip: Flip direction of selected vector lines; catadd: Set new categories to selected vector features for defined layer; catdel: Delete categories from selected vector features for defined layer; merge: Merge selected vector lines; break: Break/split vector lines; snap: Snap vector features in given threshold; connect: Connect two lines; extend: Extend lines; extendstart: Extend start nodes; extendend: Extend end nodes; chtype: Change feature type (point<->centroid, line<->boundary); vertexadd: Add new vertex to selected vector lines; vertexdel: Remove vertex from selected vector lines; vertexmove: Move vertex of selected vector lines; areadel: Delete selected areas from vector map (based on selected centroids); zbulk: Z bulk-labeling (automated assignment of z coordinate to vector lines); select: Select lines and print their ID's
input=name: Name of file containing data in GRASS ASCII vector format; '-' for standard input
move=x,y,z: Difference in x,y,z direction for moving feature or vertex
threshold=float[,float,...]: Threshold distance (coords,snap,query); '-1' for threshold based on the current resolution settings; Default: -1,0,0
ids=range: Feature ids; Example: 1,3,7-9,13
cats=range: Category values; Example: 1,3,7-9,13
coords=x,y[,x,y,...]: List of point coordinates
bbox=x1,y1,x2,y2: Bounding box for selecting features
polygon=x,y[,x,y,...]: Polygon for selecting features
where=sql_query: WHERE conditions of SQL statement without 'where' keyword; Example: income < 1000 and population >= 10000
query=string: Query tool; For 'shorter' use negative threshold value, positive value for 'longer'; Options: length, dangle; length: Select only lines or boundaries shorter/longer than threshold distance; dangle: Select dangles shorter/longer than threshold distance
bgmap=name[,name,...]: Name of background vector map(s)
snap=string: Snap added or modified features in the given threshold to the nearest existing feature; Options: no, node, vertex; Default: no; no: Not apply snapping; node: Snap only to node; vertex: Allow snapping also to vertex
zbulk=value,step: Starting value and step for z bulk-labeling; Pair: value,step (e.g. 1100,10)

DESCRIPTION

The module v.edit allows the user to edit a vector map via command line interface.

v.edit supports only "simple" vector features: points, centroids, lines and boundaries. Currently, only 2D vector features (except of tool zbulk) are supported.

Provides editing features' geometry. Attribute data connected to the vector map are not modified at all.

Vector features can be selected either by internal id, category number cats, coordinates coords, bounding box bbox, polygon, where statement (attribute data) or by query. Selecting features by coordinates is affected by the current 2D resolution or by the threshold distance given by threshold. The options are orthogonal, i.e. can be used in various combinations. For example:

v.edit map=roads tool=select \
  coord=599505,4921010,603389.0625,4918292.1875 \
  threshold=10000 where="label='interstate'"

selects all features (and prints their id's to standard output) covered by two bounding boxes (center at 599505,4921010 and 603389.0625,4918292.1875, size 2*10000) with attribute label='interstate'.

NOTES

If no vector features are selected or the flag -t is used, topology is not build at the end.

USAGE

Feature selection

Vector features can be selected in several ways:

ids - using internal (unique) feature id's
cats - using category numbers
coords - using x,y coordinate pairs (center of bounding box, size defined by threshold)
bbox - using bounding box
polygon - using polygon (at least 3 coordinate pairs have to be set)
where - using where statement (attribute data)
query - special query (e.g. minimal vector line length)

Additional parameters for vector feature specification are:

layer - layer number (currently used only with cats or where option)
threshold - threshold distance used for selecting vector features by coordinates

Tool description

create - Create new (empty) vector map (see also v.in.ascii). Optionally vector features (in GRASS ASCII vector format) can be read from standard input (input=-) or from the text file given by the input option.
add - Add new vector features (defined in GRASS ASCII vector format) to existing vector map. Features can be read from standard input or from the given text file (input option). If no header is given, the -n flag must be used. Added features can be snapped (defined by snap parameter) to nodes or vertices based on threshold distance threshold.
delete - Delete selected vector features from existing vector map.
copy - Make identical copy of selected vector features. If background map bgmap is given copy features from background map, not from currently modified vector map.
move - Move selected features of existing vector map relatively to their current location. This tool requires move option. The option defines coordinates of the movement direction. Moved features can be snapped (defined by snap parameter) to nodes or vertices based on threshold distance threshold.
flip - Flip direction of selected vector lines (lines or boundaries).
catadd - Add new layer category(ies) to selected vector feature(s). Category can be later used for new database entry.
catdel - Delete layer category(ies) of selected vector feature(s).
merge - Merge (at least two) selected vector lines or boundaries. The geometry of the merged vector lines can be changed. If the second line from two selected lines is in opposite direction to the first, it will be flipped. See also module v.build.polylines.
break - Split given vector line or boundary into two lines on location given by coords. If coords not given, breaks all selected lines at each intersection (based on v.clean, tool=break).
snap - Snap vector features in given threshold. See also module v.clean. Note that this tool supports only snapping to nodes. Parameters snap and bgmap are ignored.
connect - Connect selected lines or boundaries, the first given line is connected to the second one. The second line is broken if necessary. The lines are connected only if distance between them is not greater than snapping threshold distance threshold.
extend - Extend selected lines or boundaries without changing the current shape. Similar to connect, but the first and second lines are both extended until they intersect. The second line is broken if necessary. The lines are extended only if distance between them is not greater than snapping threshold distance threshold. If the first and second lines are parallel and do not intersect, no lines are extended. Use the -p flag to extend the first line across the parallel gap.
extendstart - Similar to extend, but extend at start nodes only. Start nodes are used to select the second line and the end node of that line can also be extended if it is within the snapping threshold distance given by threshold.
extendend - Similar to extend, but extend at end nodes only.
chtype - Change feature type of selected geometry objects. Points are converted to centroids, centroids to points, lines to boundaries and boundaries to lines.
vertexadd - Add vertex(ces) to the given vector lines or boundaries. Location of the new vertex is given by coord option. If -1 is given only first found line or boundary in bounding box is modified.
vertexdel - Remove vertex(ces) specified by coords option. If -1 is given only first found line or boundary in bounding box is modified.
vertexmove - Move vertex(ces) specified by coords option. Direction of the movement is specified by the move option. If -1 is given only first found line or boundary in bounding box is modified. Moved vertex can be snapped (defined snap) to nodes or vertices based on threshold distance threshold.
zbulk - Assign z coordinate to 3D vector lines in given bounding box. The first found line will get z coordinate based on value given by zbulk parameter. Z coordinate of other selected lines will be increased by step given by zbulk parameter. This tool strictly requires bbox and zbulk parameter. Also input vector map must be 3D.
select - Print comma separated list of selected line id's. No editing is done.

EXAMPLES

Create new vector map

Create new (empty) vector map:

v.edit tool=create map=vectmap

Create new vector map and read data from file 'roads.txt':

v.out.ascii in=roads format=standard > roads.txt;
v.edit tool=create map=vectmap input=roads.txt

or alternatively

cat roads.txt | v.edit tool=create map=vectmap input=-

Add new features to existing vector map

Add a new point to the vector map (without header):

echo "P 1 1
 640794 214874
 1 1" | v.edit -n tool=add map=vectmap input=-

# insert new row for each category in attribute table if doesn't exist yet
v.to.db map=vectmap option=cat

The input must be in GRASS ASCII vector format.

Add new features read from standard input:

v.out.ascii in=railroads format=standard | v.edit tool=add map=vectmap input=-

Delete selected features from vector map layer

Remove all vector features with category number 1 or 2:

v.edit tool=delete map=roads cats=1,2

Remove all vector features except of those with category number 1 or 2 (reverse selection):

v.edit -r tool=delete map=roads cats=1,2

Remove features with category 1 or 2 located on coordinates 600952.625,4926107 (bounding box based on the current 2D resolution):

g.region -d;
v.edit tool=delete map=roads cats=1,2 coords=600952.625,4926107

Remove all features with category 1 and 2 covered by two bounding boxes (center coordinates 592542.892,4924766.996 and 603389.062,4918292.187, size 1000 map units):

v.edit map=roads tool=delete \
  coord=592542.892,4924766.996,603389.062,4918292.187 \
  threshold=1000 cat=1,2

Copy selected features from background map

Copy all features with category number 1 from background map:

v.edit map=roads tool=copy bgmap=archsites cat=1

Move features

Move feature (vector point) located on coordinates 602580,4918480 to coordinates 603580,4919480:

v.edit tool=move map=archsites coord=602580,4918480 th=1e-2 move=1000,1000

Move all features with category 1 1000 map units to the west and 1000 map units to the south. Moved features snap to nodes in threshold distance 10 map units:

v.edit tool=move map=roads cat=1 move=1000,-1000 snap=node threshold=-1,10

Move all features defined by bounding box 601530,4921560,602520,4922310 (W,S,E,N) 1000 map units to the east and 1000 map units to the north:

v.edit tool=move map=roads bbox=601530,4921560,602520,4922310 move=-1000,1000

Flip direction of vector lines

Flip direction of all vector lines:

v.edit tool=flip map=streams cats=1-9999 type=line

Add / delete layer category number

Add new layer/category 2/1, 2/3, 2/4, 2/5 to features covered by given polygon:

v.edit tool=catadd map=roads \
  polygon=599877.75,4925088.375,597164.812,4922524.5,601338.562,4920914.625 \
  layer=2 cat=1,3-5

Delete layer/category 1/1, line id 1:

v.edit tool=catdel map=roads id=1 cats=5

Merge lines

Merge two lines with given category number:

v.edit map=roads tool=merge cat=4

Split line on given point

Split line id 810 on coordinates 604268,4923570 in threshold 50 map units:

v.edit map=roads tool=break coords=604268,4923570 id=810 threshold=50

Break selected lines at each intersection

Break selected lines (with category number 1) at each intersection:

v.edit map=roads tool=break cat=1

Snap lines

Snap all lines using threshold distance 20 map units:

v.edit map=roads id=1-9999 tool=snap threshold=-1,20 type=line

Connect lines

Connect line id 48 to line id 565:

v.edit map=roads tool=connect id=48,565

Connect line id 48 to line id 565; line id 60 to line id 50. Maximum threshold distance is 700 map units:

v.edit map=roads tool=connect id=48,565,60,50 threshold=-1,700

Add vertex

Add new vertex to the line located at 600952,4926107, threshold is set to 1 map unit:

v.edit tool=vertexadd map=roads coords=600952,4926107 threshold=1

Delete vertices

Delete vertex located at 593191.608,4925684.849 (threshold set to 0.1 map units). Modify only lines with category 1:

v.edit tool=vertexdel map=roads coord=593191.608,4925684.849 \
  threshold=1-e1 cats=1

Move vertices

Move vertices located at 604441,4921088 (threshold set to 100 map units). Modify only lines with categories 1-10:

v.edit tool=vertexmove map=roads cats=1-10 coord=604441,4921088 \
  threshold=100 move=1000,1000

Select features and print their id's

Print id's of selected features, e.g.:

v.edit map=soils@PERMANENT tool=select \
  bbox=595733.8125,4919781.75,598536.1875,4917396.75 --q

Example with d.vect:

d.erase;
d.vect roads;
d.vect -i map=roads cats=`v.edit map=roads tool=select \
  coord=592542.89243878,4924766.99622811,603389.0625,4918292.1875 \
  threshold=1000 --q` col=red

Select all lines shorter (or equal) than 10 map units:

v.edit map=roads tool=select query=length threshold=-1,0,-10

Select from given bounding box all lines longer then 200 map units:

v.edit map=roads tool=select bbox=598260,4919730,605100,4926240 query=length threshold=-1,0,200

Fix height of contours

Intput vector map contains 2D lines representing contours. Height can be assign to the contours using tool zbulk. First of all 2D lines need to be converted to 3D lines:

v.extrude input=line2 output=line3 height=0 type=line

All lines which intersect with the line given by coordinates will be modified. First found line will get height 1000 map units, height of other selected lines will be increased by 10 map units.

v.edit a2 tool=zbulk bbox=586121.25049368,4911970.21547109,603092.60466035,4927071.25713776 \
   zbulk=1000,10

AUTHORS

Original author: Wolf Bergenheim - independent developer
Initial updates: Jachym Cepicky, Mendel University of Agriculture and Forestry in Brno, Czech Republic
Major update by Martin Landa, FBK-irst (formerly ITC-irst), Trento, Italy

Last changed: $Date$

SOURCE CODE

Available at: v.edit source code (history)