[ncl-talk] Strange Vector plotting behavior

[Rashed Mahmood]

Hi Barry:
When you do something like (::4) that means you are only keeping every
fourth data point, in other-words you are sub-setting the data before
plotting it.

Cheers,
Rashed

On Sat, May 30, 2020 at 11:44 AM Barry Lynn <barry.h.lynn at gmail.com> wrote:

> Hi Rashed:
>
> Thank you for your suggestion.  It's actually being plotted with the gsn
> routines, and I was able to thin the vectors with a value of vcMinDistanceF
> = 0.01.
>
> It remains a mystery why using the suggested approach (e.g., ::4) just
> plots some of the data (hard to tell if it actually all the remaining data)
> 1/4 of the way through the domain.
>
> It might have something to do with the fact that I zoomed the data
> (subsetted it), while the vector routine is not aware of this (smaller
> domain), but then why would it work just fine when all the data is plotted?
>
> Strange!
>
> Barry
>
> On Fri, May 29, 2020 at 7:58 PM Rashed Mahmood <rashidcomsis at gmail.com>
> wrote:
>
>> Hi Barry,
>> I have not used WRF routines so I am not sure if the following would
>> work, however, if you want to thin your vectors it is better to use the
>> resource " *vcMinDistanceF*", you might need to play with it a bit to
>> get the desired look.
>> See description here:
>> https://www.ncl.ucar.edu/Document/Graphics/Resources/vc.shtml
>>
>> Cheers,
>> Rashed
>>
>>
>>
>>
>> On Thu, May 28, 2020 at 5:30 AM Barry Lynn via ncl-talk <
>> ncl-talk at ucar.edu> wrote:
>>
>>> Hello:
>>>
>>> I left out the text.
>>>
>>> Before copying it, I have to mention that the cross-section is an
>>> excerpt from the entire domain. But, radar, etc, and temperature (not
>>> shown) contour correctly.  That is, temperature maps correctly.
>>>
>>> The excerpted winds seem to be mapping to just 1/4 of the domain.
>>>
>>> Hello:
>>>
>>> I am making vertical cross-sections.
>>>
>>> I wanted to map vectors onto the map, but when I thin the data to plot
>>> fewer vectors I  end up with the vectors going 1/4 of the way across,
>>> rather than just getting a thinner plotting of the vector data.
>>>
>>> The full vector plotting is without the "::4."  WIth the ::4, I get just
>>> 1/4 of the cross-section covered.
>>>
>>> These lines cause the problem.
>>>
>>>         plot_a   = gsn_vector(wks,u_plane_a
>>> (0:zmax_pos,::4),v_plane_a(0:zmax_pos,::4),vecres)
>>>
>>>         plot_b   =
>>> gsn_vector(wks,u_plane_b(0:zmax_pos,::4),v_plane_b(0:zmax_pos,::4),vecres)
>>>
>>>         plot_c   =
>>> gsn_vector(wks,u_plane_c(0:zmax_pos,::4),v_plane_c(0:zmax_pos,::4),vecres)
>>>
>>>
>>> I have attached the code.  I am not sure why this doesn't work, since it
>>> generally works as advertised.  One comment: I am subsetting the u,v data
>>> before plotting it.
>>>
>>>
>>> Code attached.  Sorry it's so long!
>>>
>>> On Thu, May 28, 2020 at 2:00 PM Barry Lynn <barry.h.lynn at gmail.com>
>>> wrote:
>>>
>>>>
>>>>
>>>> --
>>>> Barry H. Lynn, Ph.D
>>>> Senior Associate Scientist, Lecturer,
>>>> The Institute of the Earth Science,
>>>> The Hebrew University of Jerusalem,
>>>> Givat Ram, Jerusalem 91904, Israel
>>>> Tel: 972 547 231 170
>>>> Fax: (972)-25662581
>>>>
>>>> C.E.O, Weather It Is, LTD
>>>> Weather and Climate Focus
>>>> http://weather-it-is.com
>>>> Jerusalem, Israel
>>>> Local: 02 930 9525
>>>> Cell: 054 7 231 170
>>>> Int-IS: x972 2 930 9525
>>>>
>>>>
>>>
>>> --
>>> Barry H. Lynn, Ph.D
>>> Senior Associate Scientist, Lecturer,
>>> The Institute of the Earth Science,
>>> The Hebrew University of Jerusalem,
>>> Givat Ram, Jerusalem 91904, Israel
>>> Tel: 972 547 231 170
>>> Fax: (972)-25662581
>>>
>>> C.E.O, Weather It Is, LTD
>>> Weather and Climate Focus
>>> http://weather-it-is.com
>>> Jerusalem, Israel
>>> Local: 02 930 9525
>>> Cell: 054 7 231 170
>>> Int-IS: x972 2 930 9525
>>>
>>> _______________________________________________
>>> ncl-talk mailing list
>>> ncl-talk at ucar.edu
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>
>>
>
> --
> Barry H. Lynn, Ph.D
> Senior Associate Scientist, Lecturer,
> The Institute of the Earth Science,
> The Hebrew University of Jerusalem,
> Givat Ram, Jerusalem 91904, Israel
> Tel: 972 547 231 170
> Fax: (972)-25662581
>
> C.E.O, Weather It Is, LTD
> Weather and Climate Focus
> http://weather-it-is.com
> Jerusalem, Israel
> Local: 02 930 9525
> Cell: 054 7 231 170
> Int-IS: x972 2 930 9525
>
>
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