[mapserver-users] color attribute question

[Do Wi]

hi, thanks allot!
that is exactly what i did after another user suggested it ( Cristiano
Sumariva ).

here it is for reference:

CREATE OR REPLACE FUNCTION temp.ms_colorMath( percentile double precision )
RETURNS  varchar
LANGUAGE plpgsql
AS
$$
DECLARE
C double precision;
X double precision;
m double precision;
H int;
V double precision;
S double precision;

R int;
G int;
B int;
BEGIN
--see here http://www.rapidtables.com/convert/color/hsv-to-rgb.htm
--if H != 0 need to change the function
--curently - red gradient
S := percentile;
IF (S < 0.1 AND S > 0)  THEN S := 0.1; END IF;
 H := 0;
V := 1.0;
C := V * S;
X := C * (1-abs(mod(H/60,2)-1));
m := V-C;

R := ((C + m)*255 )::int;
G := ((X + m)*255 )::int;
B := ((0 + m)*255 )::int;

 RETURN (R)::text || ' ' || (G)::text || ' ' || (B)::text;
END
$$;


On Thu, Jun 26, 2014 at 6:24 PM, Carlos Ruiz <boolean10001 at yahoo.com> wrote:

> To achieve more flexibility as you want, you have to code a function with
> PL/pgSQL in PostgreSQL or with PHP/Python/Java/C# with Mapscript to define
> which is the base color (red, green, blue, yellow ...) and then to
> calculate the percent in the right RGB channel.
>
>
> Cheers
>
> Mtro. Carlos Ruiz
>
> --------------------------------------------
> On Mon, 6/23/14, Do Wi <dowi84 at gmail.com> wrote:
>
>  Subject: Re: [mapserver-users] color attribute question
>  To: "Carlos Ruiz" <boolean10001 at yahoo.com>
>  Date: Monday, June 23, 2014, 2:56 PM
>
>  thanks allot!
>  Steve and another user here mentioned this path
>  and it did work!only problem is that it cannot be
>  changed later if for example the user chooses a blue
>  gradient.
>
>  how will i go about doing it with
>  mapscript?
>  maybe it relates to my question herehttp://
> gis.stackexchange.com/questions/102862/when-to-choose-mapscript-over-mapfile-or-vice-versa
>
>
>  :-)
>  thanks allot!dovi
>
>  On Mon, Jun 23, 2014
>  at 6:13 PM, Carlos Ruiz <boolean10001 at yahoo.com>
>  wrote:
>
>
>  Do,
>  If
>  you want to do this without using mapscript, you can pull
>  the gradient calculation as an attribute from your data
>  table.
>
>
>  ALTER TABLE mytable ADD COLUMN gradient_color
>  VARCHAR;
>  UPTATE mytable SET gradient_color = floor(gradient *
>  255)::text || ' 0 0';
>
>  Cheers
>
>   Mtro. Carlos Ruiz
>
>
>
>  On Monday, June 23, 2014 4:59 PM, "Lime, Steve D
>  (MNIT)" <Steve.Lime at state.mn.us>
>  wrote:
>
>
>
>
>
>  You can compute a color
>  string using PostgreSQL string functions:
>
>    SELECT percentage ||
>  ‘ 0 0’ AS color FROM …
>
>  Steve
>
>  From: mapserver-users-bounces at lists.osgeo.org
>  [mailto:mapserver-users-bounces at lists.osgeo.org]
>  On Behalf Of Do Wi
>
>  Sent: Sunday, June 22, 2014 3:50 PM
>
>  To: mapserver-users at lists.osgeo.org
>
>  Subject: [mapserver-users] color attribute
>  question
>
>
>  hi!
>
>
>
>
>  i have this
>  scenario:
>
>
>  i have a column in my
>  postgis table which contains a double representing a
>  percentage.
>
>
>
>
>
>  i want to color my
>  polygons in a gradient fashion based on that
>  number.
>
>
>
>
>
>  the docs states three
>  ways to specify color:
>
>
>  1. three [1-255]
>  numbers
>
>
>  2. hex
>  string
>
>
>  3.
>  [attribute]
>
>
>
>
>
>  but the attribute must
>  be a string by itself in the same format as options 1 or
>  2.
>
>
>
>
>
>  how can i achieve
>  something like
>
>
>
>
>
>  COLOR [percentage]*255 0
>  0
>
>
>  or
>
>
>  COLOR [percentage] 0
>  0
>
>
>  if percentageis already
>  0..255
>
>
>
>
>
>  for a red gradient for
>  example?
>
>
>
>
>
>  thanks
>  allot!
>
>
>
>
>  _______________________________________________
>  mapserver-users mailing list
>  mapserver-users at lists.osgeo.org
>
>  http://lists.osgeo.org/mailman/listinfo/mapserver-users
>
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