Re: [ferret_users] Color_vector.jnl

[Russ Fiedler <russell.fiedler@xxxxxxxx>]

Hi Penny,

If you aren't trying to overlay the flow pattern over some other quantity then you could shade the magnitude of the vectors (i.e. the speed)  and then overlay the flow lines. This will result in a similar effect though probably not as nice as colouring the lines themselves.

e.g.

let speed=(u^2+v^2)^0.5
shade speed
vec/flow/ov u,v

Russ

On 06/08/13 19:13, Penny Driver wrote:

Hi Ansley

Thanks for the explanation! I should have guessed as much from the way the plot displays as it's made (one colour at a time). I hope someone with more expertise might take up the idea to colour flowlines to show strength of the vectors more easily.

Thanks again!

Best,
Penny

On Mon, Aug 5, 2013 at 6:43 PM, Ansley Manke <ansley.b.manke@xxxxxxxx> wrote:

Hi Penny,
The color_vector script works by plotting groups of vectors with different colors. First (for instance) it finds the shortest vectors and draws them in purple, then longer ones in blue, green, orange and finally the longest in red.

The vector/flow command isn't set up to change colors along the flow lines. Its pathline integration method needs to work on the entire vector field, and so Jaison's idea to change colors with different sets of vectors wouldn't work.  It would require internal Ferret changes in order to do what you want.  It's a good idea though, and it could be done in a way similar to the line plots colored by a value, "ribbon plots", that we implemented in recent versions of Ferret.

Ansley

On 8/3/2013 5:10 AM, Penny Driver wrote:

Hi Jaison and ferreters

I've been using the script color_vector.jnl which I found in /usr/local/ferret/contrib

! Written By : Jaison Kurian (jaison@xxxxxxxxxxxxxxxxxx, jaison@xxxxxxxxxxxxxx)
! Written On : Jan/04/2008 (based on a draft completed on May/28/2007)

to get a better view of the Walker Circulation. The first problem I encountered was that the script wasn't using my vec_yskip. I suspect this is because my y-axis is height in this case. I copied the original color_vector.jnl script to my run directory (called color_vector_z.jnl) and manually changed yskip=1 to yskip=2 which has worked out perfectly.

I'm not nearly a proficient enough programmer to fully understand the script but I was wondering if I could add the /flow option to the script somewhere? I included /flow in the vec_cmd definition but it didn't change the output. I find the flow line winds very useful except that I can't always see what the strength of the winds are. This colour coded vector script would be wonderful if I could apply it to the flowline option.

I'd really appreciate any help on this, even if it's just to tell me that I can't apply flow to this vector script. Many thanks!

Best,
Penny

I'm using model output and this is the plot script I'm using:

   let uu = u[d=17,y=-5,l=1:3@ave]*2
   let vv = omega[d=17,y=-5,l=1:3@ave]*-600
   set reg/x=-180:180

   define symbol vec_cmd      = vector/nolab/vlimits=26:1/flow
   define symbol vec_u        = uu                ! u var name, no [],(),*,/,+,-, ^ stuff
   define symbol vec_v        = vv                ! v var name, no [],(),*,/,+,-, ^ stuff
   define symbol vec_len      = 50               ! value for /LENGTH qualifier
   define symbol vec_xskip    = 15              ! value for /XSKIP qualifier
   define symbol vec_yskip    = 4                ! value for /YSKIP qualifier
   define symbol vec_arrowkey = NO           ! YES or NO, for scale/key vector
   define symbol vec_veckey   = 325,78,,(f4.1, " m/s")! arguments to "PPL VECKEY" command
   define symbol vec_lo       = 0                   ! low   value for color levels
   define symbol vec_hi       = 60                  ! high  value for color levels
   define symbol vec_delta    = 2                  ! delta value for color levels
   define symbol vec_pal      = rainbow          ! palette file name
   define symbol vec_colorkey = YES           ! YES or NO, for color bar/key
   define symbol vec_shakey   = 1,1,0.12,2   ! arguments to "PPL SHAKEY" command
   define symbol vec_otherppl = none      !other ppl commands (should start with "ppl"),
                                                            !   for example
                                                            !   ppl xfor (f5.1, ''lonE'')


   go color_vector_z