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) $

       Full index

       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                                     v.colors(1grass)