NAME

       v.colors  - Set color rules for features in a vector using a numeric attribute column.

KEYWORDS

       vector, color table

SYNOPSIS

       v.colors
       v.colors help
       v.colors    [-sn]    map=name    column=string     [layer=integer]     [rgb_column=string]
       [range=min,max]     [color=style]     [raster=string]      [rules=string]      [--verbose]
       [--quiet]

   Flags:
       -s
           Save placeholder raster map for use with d.legend

       -n
           Invert colors

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       map=name
           Name of input vector map

       column=string
           Name of column containing numeric data

       layer=integer
           Layer number of data column
           Default: 1

       rgb_column=string
           Name of color column to populate
           Default: GRASSRGB

       range=min,max
           Manually set range (min,max)

       color=style
           Type of color table
           Options:
           aspect,aspectcolr,bcyr,bgyr,byg,byr,celsius,corine,curvature,differences,elevation,etopo2,evi,gdd,grey,grey1.0,grey255,grey.eq,grey.log,gyr,ndvi,population,precipitation,rainbow,ramp,random,ryb,ryg,sepia,slope,srtm,terrain,wave

       raster=string
           Raster map name from which to copy color table

       rules=string
           Path to rules file

DESCRIPTION

       v.colors  allows  the  user  to create and/or modify the color table for a vector map. The
       vector map (specified on the command line by map) must exist in the user's current  mapset
       search path.

       As  input  a  vector map with a numeric data column is required which is used to apply the
       color rules. The color values are stored in a  string  column  (default  name  "GRASSRGB",
       varchar(11))  by  saving the RRR:GGG:BBB values suitable for use with 'd.vect -a'. If this
       RGB column is not found in the attribute table, it is automatically created.

       How it works: it creates a dummy raster map with the  same  data  range  as  the  vector's
       column  then  runs  r.colors  for that temporary map.  It then uses r.what.colors for each
       value found by v.db.select and uploads it a new  column  in  the  vector  map's  attribute
       database.

       It  is  planned  that  this  script will be replaced with a C display module which renders
       thematic vector maps directly instead requiring the overhead of saving the colors into the
       DB.

       If  the  target  column  name  given  by  the rgb_column option does not exist, it will be
       created. The default name is "GRASSRGB".

EXAMPLES

       Creating a random sample point map, query raster map values for those points, and colorize
       output:
       # Spearfish dataset
       g.region -d
       v.random out=rand5k_elev n=5000
       v.db.addtable map=rand5k_elev column='elevation double precision'
       v.what.rast vector=rand5k_elev raster=elevation.10m column=elevation
       v.colors map=rand5k_elev column=elevation color=bcyr
       # See some GRASSRGB values:
       v.db.select rand5k_elev | head -n 4
       cat|elevation|GRASSRGB
       1|1609.643677|255:210:0
       2|1347.657959|34:255:221
       3|1142.30835|0:81:255
       4|1212.105469|0:152:255
       # display colorized points map
       d.mon x0
       d.vect -a rand5k_elev

       Colorizing the roads map in Spearfish:
       g.copy vect=roads,myroads
       echo "1 red
       2 yellow
       3 orange
       4 black
       5 grey" > colors.txt
       v.colors myroads column=cat rules=colors.txt
       # display colorized roads map
       d.mon x0
       d.vect -a myroads

       Colorizing a TIN (polygons) generated by v.delaunay:
       # new columns for x,y,z of centroids
       v.db.addtable map=tin \
          columns="east  double  precision,  north  double  precision,  height  double precision,
       GRASSRGB varchar(11)"
       # transfer geometry for colorizing (we need the centroid height)
       v.to.db tin option=coor columns="east,north,height"
       v.db.select tin
       v.colors tin column=height rgb_column=GRASSRGB color=rainbow
       # display colorized triangles
       d.mon x0
       d.vect -a tin

SEE ALSO

        d.vect -z, r.colors, r.colors.stddev, r.what.color, v.db.addcol, v.db.select, db.execute

       See also wiki page Color tables (from GRASS User Wiki)

       ColorBrewer is an online tool designed to help people select good color schemes  for  maps
       and other graphics.

AUTHOR

       Hamish Bowman
       Dunedin, New Zealand

       Last changed: $Date: 2013-02-15 14:04:18 -0800 (Fri, 15 Feb 2013) $

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       © 2003-2013 GRASS Development Team