[GRASS-user] r.colors

[Nathan Barber - NOAA Federal]

Background

We generate a precipitation graphic that is based on the mean of an
ensemble of models.  Because it goes out 16 days, we can have a wide
variety of amounts...sometimes it can be as little as 2 inches other times
it can be as great as 6 or 7.  This variability can cause some issues with
users when our color scale always changes relative to the amounts.  For
example Day 1, 1 inch is yellow and 3 inches is purple....Day 2, 2 inches
is yellow and 6 inches is purple.

Is there a way to categorize amounts, say 0-1, 1-2, 2-3, 4-5, 5-6, 7+ so
that purple will always represent 7+ and yellow will always be 0-1,
etc...I've looked at the r.colors wiki page but I can't seem to get the
rules to work correctly.  I need a consistent color scheme for the graphic
that communicates the level of concern properly to the user.

Any examples would be greatly appreciated...Thanks.

-- 
Nathan Barber
Hydrologist
NOAA National Weather Service
Ohio River Forecast Center <http://www.erh.noaa.gov/ohrfc/>
1901 S State Rt 134
Wilmington, OH  45177
(937) 383-0528
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