[GRASS-dev] [grass-code R][382] v.colors wish

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code R item #382, was opened at 2007-04-25 22:35
Status: Open
Priority: 3
Submitted By: Markus Neteler (markusn)
Assigned to: Nobody (None)
Summary: v.colors wish
Issue status: None
GRASS component: vector
Operating system: all
Operating system version:

Initial Comment:
A v.colors module (script?) is desired which helps to easily colorize
vector maps.

v.colors vectormap column=name color=rulesfile

where
- column defines the column to use for colorization
- color defines a file to the list of attribute-color matches

The principal steps will be:

1. v.db.addcol vectormap col="GRASSRGB varchar(11)"

2. read color definition in the style
     attribute1 color1
     attribute2 color2
     ...

     with
       - attributeX be existing attribute in specified column
       - colorX be color name (from X11 color list?) or RGB pattern

3. if needed, translate color names to RRR:GGG:BBB values

4. update attribute table column GRASSRGB
   loop over all lines in rulesfile, doing
      v.db.update vectormap col=GRASSRGB val="RRR:GGG:BBB" where="column=attributeX"

Maybe rather easy to do, some scripting...

Markus

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code R item #382, was opened at 2007-04-25 22:35
Submitted By: Markus Neteler (markusn)
Summary: v.colors wish

..

A v.colors module (script?) is desired which helps to easily colorize
vector maps.

v.colors vectormap column=name color=rulesfile

where
- column defines the column to use for colorization
- color defines a file to the list of attribute-color matches

The principal steps will be:

1. v.db.addcol vectormap col="GRASSRGB varchar(11)"

2. read color definition in the style
     attribute1 color1
     attribute2 color2
     ...

     with
       - attributeX be existing attribute in specified column
       - colorX be color name (from X11 color list?) or RGB pattern

3. if needed, translate color names to RRR:GGG:BBB values

4. update attribute table column GRASSRGB
   loop over all lines in rulesfile, doing
      v.db.update vectormap col=GRASSRGB val="RRR:GGG:BBB"
      where="column=attributeX"

Maybe rather easy to do, some scripting...

Date: 2007-05-03 18:31
Sender: Hamish

A v.colors module (script?)

It is hard to do (efficiently) inside a script alone, as you
need to do some math to interpolate between the rule values for
each data point.

Suggestion: r.what.colors could be expanded to include a
colors=/rules= option to query the color for some value= based
on a predefined rules file instead of a raster map? Then you feed
all the values to be queried to r.what.colors via stdin, and get
a nice list of RRR:GGG:BBB to give to v.db.update.

Instead of v.db.update, write the SQL update statements to a $TMP
file (with ";" at each EOL) then use a single call to db.execute input=,
as this will be much much faster. (see v.in.garmin)

Hamish

ps- this would be really cool for "snail trail" plots
for a geolocated time series of vector point data.

(I have a matlab[/octave] script somewhere that does this
interpolation already, for this same purpose)