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v.mkgrid(1)		    GRASS GIS User's Manual		   v.mkgrid(1)

       v.mkgrid	 - Creates a vector map	of a user-defined grid.

       vector, geometry, grid, point pattern, hexagon

       v.mkgrid	--help
       v.mkgrid	  [-had]   map=name   [grid=rows,columns]    [position=string]
       [coordinates=east,north]	       [box=width,height]	 [angle=float]
       [breaks=integer]	  [type=string]	  [--overwrite]	 [--help]  [--verbose]
       [--quiet]  [--ui]

	   Create hexagons (default: rectangles)

	   Allow asymmetric hexagons

	   EXPERIMENTAL: Add diagonals to rectangular lines
	   Applies only	to lines for rectangles

	   Allow output	files to overwrite existing files

	   Print usage summary

	   Verbose module output

	   Quiet module	output

	   Force launching GUI dialog

       map=nameA [required]
	   Name	for output vector map

	   Number of rows and columns in grid

	   Where to place the grid
	   Options: region, coor
	   Default: region
	   region: current region
	   coor: use 'coor' and	'box' options

	   Lower left easting and northing coordinates of map

	   Width and height of boxes in	grid

	   Angle of rotation (in degrees counter-clockwise)
	   Default: 0

	   Number of vertex points per grid cell
	   Options: 0-60
	   Default: 0

	   Output feature type
	   Options: point, line, area
	   Default: area

       v.mkgrid	creates	a vector map representation of	a  regular  coordinate
       grid. Point, line, and area vector grids	can be created.

       Grid  points  created  with the type=point option will be placed	at the
       center of each grid cell, like centroids	with the default type=area op-

       Grid  lines  created with the type=line option will be identical	to the
       edges of	each grid cell,	like boundaries	with the default type=area op-

       The  resultant  grid  can  be  rotated around the origin	(center	of the
       grid) with the angle option.

       Optionally hexagons can be created with the -h flag.  Hexagons  are  by
       default symmetric. Asymmetric hexagons can be allowed with the -a flag.

       This module is NOT to be	used to	generate a vector map of USGS quadran-
       gles, because USGS quads	are not	exact rectangles.

   Creating a global grid in a latitude-longitude
       To be run in a latitude-longitude location (WGS84)
       # set the region:
       g.region	n=90 s=-90 w=-180 e=180	res=10 -p
       projection: 3 (Latitude-Longitude)
       zone:	   0
       datum:	   wgs84
       ellipsoid:  wgs84
       north:	   90N
       south:	   90S
       west:	   180W
       east:	   180E
       nsres:	   10
       ewres:	   10
       rows:	   18
       cols:	   36
       cells:	   648
       # create	10 degree size grid:
       v.mkgrid	map=grid_10deg
       # create	20 degree size grid:
       v.mkgrid	map=grid_20deg box=20,20

   Creating a grid in a	metric projection
       Creating	a 4x3 grid, cells 20km a  side,	 with  lower  left  corner  at
       v.mkgrid	map=coro_grid grid=4,3 position=coor coordinates=2716500,6447000 box=20000,20000

   Creating a positioned grid in a latitude-longitude
       Creating	 a 10x12 lat/lon grid, cells 2 arc-min a side, with lower left
       corner at 167deg	52min east, 47deg 6min south. For use with  e.g.  QGIS
       you  can	 then pull this	grid into a projected location with v.proj be-
       fore exporting as a Shapefile with  v.out.ogr  (within  GRASS  GIS  you
       could  just  use	d.grid -w from the projected location for the same ef-
       v.mkgrid	map=p2min_grid grid=10,12 position=coor	coordinates=167:52E,47:06S box=0:02,0:02

   Creating a simple point pattern
       North Carolina sample dataset example, creating a 1km spaced point grid
       based on	the current region extent defined by the "elevation" map:
       g.region	raster=elevation res=1000 -pa
       v.mkgrid	type=point map=pointpattern

   Creating a regular point pattern
       North  Carolina sample dataset example, creating	a regular spaced point
       grid based on the current region	extent defined by the "elevation" map,
       using a two-step	approach:
       # create	first set of points, covering extent of	"elevation" raster map
       g.region	raster=elevation res=1000 -pa
       v.mkgrid	type=point map=pointpattern1
       # shift grid by half point distance (map	units)
       g.region	n=n+500	w=w+500	e=e+500	s=s+500	-p
       # create	second set of points
       v.mkgrid	type=point map=pointpattern2
       # merge into final point	pattern
       v.patch input=pointpattern1,pointpattern2 output=pointpattern3
       Different point patterns	for sampling design

   Creating hexagons in	a metric projection
       North  Carolina sample dataset example, creating	regular	hexagons based
       on the current region extent defined by the "elevation" map and	raster
       resolution for the hexagon size:
       g.region	raster=elevation res=5000 -pa
       v.mkgrid	map=hexagons -h
       d.grid 5000
       Hexagon map

   Using hexagons for point density
       To  compute  point  density  in	a  hexagonal  grid  for	the vector map
       points_of_interest in the basic North Carolina sample dataset, the vec-
       tor  map	itself is used to set extent of	the computational region.  The
       resolution is based on the desired size of hexagons.
       g.region	vector=points_of_interest res=2000 -pa
       The hexagonal grid is created as	a vector map based on  the  previously
       selected	extent and size	of the grid.
       v.mkgrid	map=hexagons -h
       The  following  counts  the  number  of	points	per  hexagon using the
       v.vect.stats module.
       v.vect.stats points=points_of_interest areas=hexagons count_column=count
       User should note	that some of the points	may be outside the grid	 since
       the  hexagons  cannot cover all the area	around the edges (the computa-
       tional region extent needs to be	enlarged if all	points should be  con-
       sidered).   The last command sets the vector map	color table to viridis
       based on	the count column.
       v.colors	map=hexagons use=attr column=count color=viridis
       Point density in	a hexagonal grid

	d.grid,, v.patch, v.vect.stats

       Michael Higgins,	U.S.Army Construction Engineering Research Laboratory

       Update for new vectors Radim Blazek 10/2004

       Available at: v.mkgrid source code (history)

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       index | Full index

       A(C) 2003-2020 GRASS Development	Team, GRASS GIS	7.8.3 Reference	Manual

GRASS 7.8.3							   v.mkgrid(1)


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