Re: [ferret_users] Strange dots from VECTOR command

[Ansley Manke <a.c.manke@xxxxxxxxx>]

Hi Ryo,

In vector plotting, if the vector magnitude is 0 then the vector plot has a tiny dot at those locations.  In classic Ferret, there was a  graphics element for the tiniest dot that could be drawn, and that is what was used.  As I recall, the PyFerret graphics libraries did not have such an object, and so some other call was substituted.  It seems to me that in your example, the PLOT/VS call that draws a larger symbol is somehow messing up what should be the drawing of tiny dots on the subsequent vector command, making them too large.

To see how it goes, try some plots with zero-length vectors:

  vector 0*u_anom, 0*v_anom

A workaround would be a to define a mask so that locations where the vectors are 0 length either have a small non-zero value, or to set them to have missing-data to plot nothing at those places.

On 7/29/2022 9:59 AM, Ryo Furue wrote:

Dear Ferret users,

Has anybody seen this problem?  The VECTOR command plots some black dots as can be seen below. Run the attached Ferret script like so

pyferret -nodisplay -script try2.jnl

I also attach the datafile that the script uses.

These dots are very sensitive. If I change something, they are often gone but occasionally there are many more of them.  (That's why I couldn't simplify the problem further.)

macOS 12.4 & 12.5

PyFerret v7.63 (optimized); Darwin 19.6.0 - 10/13/20

Best regards,

Ryo

-----------

set data tmp.nc
shade/nokey 0*u_anom ! dummy
plot/vs/symbol/thick=3/size=0.5/color=red/nolabel/ov\
  {38.25}, {143.58333333333333333333}
vector/aspect/ov u_anom, v_anom
frame/file=tmp.png