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] [placeholder= string] [--overwrite] [--verbose] [-- quiet]

Flags:¶

-s

 

Save placeholder raster map for use with d.legend

-n

 

Invert colors

--overwrite

 

Allow output files to overwrite existing files

--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,haxby,ndvi,population,population_dens,precipitation,precipitation_monthly,rainbow,ramp,random,rstcurv,ryb,ryg,sepia,slope,srtm,terrain,wave

raster=string

 

Raster map name from which to copy color table

rules=string

 

Path to rules file

placeholder=string

 

Dummy raster map name containing color rules for use with d.legend

 

Use with the -s flag (using this option implies -s)

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 23:04:18 +0100 (Fri, 15 Feb 2013) $ Full index © 2003-2014 GRASS Development Team