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NAME

       v.colors  - Creates/modifies the color table associated with a vector map.

KEYWORDS

       vector, color table

SYNOPSIS

       v.colors
       v.colors --help
       v.colors [-rwldngac] map=name  [layer=string]  use=string  [column=name]   [range=min,max]
       [color=style]    [raster=name]     [raster_3d=name]     [rules=name]     [rgb_column=name]
       [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -r
           Remove existing color table

       -w
           Only write new color table if it does not already exist

       -l
           List available rules then exit

       -d
           List available rules with description then exit
           If a color rule is given, only this rule is listed

       -n
           Invert colors

       -g
           Logarithmic scaling

       -a
           Logarithmic-absolute scaling

       -c
           Convert color rules from RGB values to color table
           Option ’rgb_column’ with valid RGB values required

       --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
           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

       use=string [required]
           Source values
           Options: attr, cat, z
           Default: cat
           attr: read values from attribute table (requires <column> option)
           cat: use category values
           z: use z coordinate (3D points or centroids only)

       column=name
           Name of column containing numeric data
           Required for use=attr

       range=min,max
           Manually set range (refers to ’column’ option)
           Ignored when ’rules’ given

       color=style
           Name of color table
           Options: aspect, aspectcolr, bcyr, bgyr, blues, byg, byr, celsius, corine,  curvature,
           differences,  elevation,  etopo2,  evi, fahrenheit, gdd, grass, greens, grey, grey.eq,
           grey.log, grey1.0, grey255, gyr, haxby, inferno, kelvin, magma, ndvi,  ndwi,  oranges,
           plasma,     population,     population_dens,    precipitation,    precipitation_daily,
           precipitation_monthly, rainbow, ramp, random, reds, roygbiv, rstcurv, ryb, ryg, sepia,
           slope, soilmoisture, srtm, srtm_plus, terrain, viridis, water, wave
            aspect: aspect oriented grey colors [range: map values]
            aspectcolr: aspect oriented rainbow colors [range: 0 to 360]
            bcyr: blue through cyan through yellow to red [range: map values]
            bgyr: blue through green through yellow to red [range: map values]
            blues: white to blue [range: map values]
            byg: blue through yellow to green [range: map values]
            byr: blue through yellow to red [range: map values]
            celsius: blue to red for degree Celsius temperature [range: -80 to 80]
            corine: EU Corine land cover colors [range: 111 to 995]
            curvature:  for  terrain  curvatures (from v.surf.rst and r.slope.aspect) [range: map
           values]
            differences: differences oriented colors [range: map values]
            elevation: maps relative ranges of raster values to elevation color ramp [range:  map
           values]
            etopo2: colors for ETOPO2 worldwide bathymetry/topography [range: -11000 to 8850]
            evi: enhanced vegetative index colors [range: -1 to 1]
            fahrenheit: blue to red for Fahrenheit temperature [range: -112 to 176]
            gdd: accumulated growing degree days [range: 0 to 6000]
            grass: GRASS GIS green (perceptually uniform) [range: map values]
            greens: white to green [range: map values]
            grey: grey scale [range: map values]
            grey.eq: histogram-equalized grey scale [range: map values]
            grey.log: histogram logarithmic transformed grey scale [range: map values]
            grey1.0: grey scale for raster values between 0.0-1.0 [range: 0 to 1]
            grey255: grey scale for raster values between 0-255 [range: 0 to 255]
            gyr: green through yellow to red [range: map values]
            haxby: relative colors for bathymetry or topography [range: map values]
            inferno: perceptually uniform sequential color table inferno [range: map values]
            kelvin: blue to red for temperature in Kelvin scale [range: 193.15 to 353.15]
            magma: perceptually uniform sequential color table magma [range: map values]
            ndvi: Normalized Difference Vegetation Index colors [range: -1 to 1]
            ndwi: Normalized Difference Water Index colors [range: -200 to 200]
            oranges: white to orange [range: map values]
            plasma: perceptually uniform sequential color table plasma [range: map values]
            population:  color table covering human population classification breaks [range: 0 to
           2e+09]
            population_dens: color table covering human population density classification  breaks
           [range: 0 to 1e+09]
            precipitation: precipitation color table (0..2000mm) [range: 0 to 7000]
            precipitation_daily: precipitation color table (0..1000mm) [range: 0 to 10000]
            precipitation_monthly: precipitation color table (0..1000mm) [range: 0 to 1000]
            rainbow: rainbow color table [range: map values]
            ramp: color ramp [range: map values]
            random: random color table [range: map values]
            reds: white to red [range: map values]
            roygbiv:  [range: map values]
            rstcurv: terrain curvature (from r.resamp.rst) [range: map values]
            ryb: red through yellow to blue [range: map values]
            ryg: red through yellow to green [range: map values]
            sepia: yellowish-brown through to white [range: map values]
            slope: r.slope.aspect-type slope colors for raster values 0-90 [range: 0 to 90]
            soilmoisture: soilmoisture color table (0.0-1.0) [range: 0 to 1]
            srtm:  color palette for Shuttle Radar Topography Mission elevation [range: -11000 to
           8850]
            srtm_plus: color  palette  for  Shuttle  Radar  Topography  Mission  elevation  (with
           seafloor colors) [range: -11000 to 8850]
            terrain:  global  elevation  color  table covering -11000 to +8850m [range: -11000 to
           8850]
            viridis: perceptually uniform sequential color table viridis [range: map values]
            water: water depth [range: map values]
            wave: color wave [range: map values]

       raster=name
           Raster map from which to copy color table

       raster_3d=name
           3D raster map from which to copy color table

       rules=name
           Path to rules file

       rgb_column=name
           Name of color column to populate RGB values
           If not given writes color table

DESCRIPTION

       v.colors allows creating or modifying color table associated with a vector  map  similarly
       to r.colors for raster maps.

       Color  rules  are  built  from  features  category values (use=cat) or numeric data column
       (use=attr) defined by column option. For 3D vector maps is allowed to define  color  rules
       based on points or centroids z-coordinate (use=z). 3D vector lines are not supported.

       The  raster option allows user to specify a raster map from which to copy the color table,
       similarly raster_3d option for 3D raster map.

       The rules color table type will cause v.colors to read  color  table  specifications  from
       given  file  and  will  build  the  color  table accordingly. See r.colors manual page for
       details.

       If the user specifies the -w flag, the current color table file for the input map will not
       be overwritten. This means that the color table is created only if the vector map does not
       already have a color table. If this option is not  specified,  the  color  table  will  be
       created if one does not exist, or modified if it does.

       Alternatively  the color rules can be stored in a string column (rgb_column) by saving the
       RRR:GGG:BBB values suitable for use with d.vect.

NOTES

       For vector maps with a large number of features it’s more convenient to store color  rules
       in  an  attribute  column (given by rgb_column) rather then in a color table file. Reading
       color tables with more then 1000 items is slow.

EXAMPLES

   Define color table based on categories
       Define color table wave based on categories from layer 1
       v.colors map=soils_general layer=1 color=wave

   Define color table based on attribute values
       Define color table ryg based on values from attribute  column  AREA.  Attribute  table  is
       linked to layer 1.
       v.to.db map=soils_general layer=1 option=area column=AREA
       v.colors map=soils_general layer=1 color=wave use=attr column=AREA

   Define color table stored as RGB values in attribute table
       Write  color  values  to  the  attribute table (column GRASSRGB) instead of creating color
       table.
       v.colors map=soils_general layer=1 color=wave use=attr column=AREA rgb_column=GRASSRGB
       # See some GRASSRGB values:
       v.db.select map=soils_general where="cat < 4"
       cat|OBJECTID|AREA|PERIMETER|GSLNC250_|GSLNC250_I|GSL_NAME|GRASSRGB
       1|1|0|164616.125|2|1|NC113|212:42:127
       2|2|0|30785.529297|3|2|NC096|212:42:127
       3|3|0|87572.882812|4|3|NC097|212:42:127

   Convert RGB attribute values into color table
       Convert existing RGB values to color table rules.
       v.colors -c map=soils_general rgb_column=GRASSRGB
       Note that in this case the vector  map  has  a  proper  color  table  assigned  (check  by
       v.colors.out)  together  with  GRASSRGB  attribute  column.  Also note that color table is
       preferred over RGB values stored in attribute table.

   Remove existing color table
       Existing color table can be removed by -r flag.
       v.colors -r map=soils_general
       Before removing color table you can store color rules to  the  file  by  v.colors.out  and
       later to assign by rules option.
       v.colors.out map=soils_general rules=soils.colr
       v.colors map=soils_general rules=soils.colr
       To drop RGB column use v.db.dropcolumn.
       v.db.dropcolumn map=soils_general column=GRASSRGB

SEE ALSO

        d.vect, r.colors, r.colors.out, r3.colors, r3.colors.out, v.colors.out

       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.

AUTHORS

       Martin Landa, OSGeoREL, Czech Technical University in Prague, Czech Republic

       Last changed: $Date: 2015-02-13 16:14:07 +0100 (Fri, 13 Feb 2015) $

SOURCE CODE

       Available at: v.colors source code (history)

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