[ncl-talk] wind vector

[Xi Chang]

Thanks guys,
Im using this a work-around prior to plot the vector,

u = where(sqrt(u*u + v * v) .lt. min_magnitude, u at _FillValue, u)
v = where(sqrt(u*u + v * v) .lt. min_magnitude, v at _FillValue, v)

but the results are not the same as the use of  *res at vcMinMagnitudeF *
thanks

On Wed, Dec 10, 2014 at 8:47 PM, David Brown <dbrown at ucar.edu> wrote:

> Kyle is definitely correct in saying that "curly vectors are more akin
> to streamlines". In fact at the low level, a modified version of the
> streamline code is used to implement them. That is also why the
> vcMinMagnitudeF is not currently enabled for curly vectors. However,
> since each curly vector originates from a specific grid point where a
> single vector magnitude can be computed, it seems to me that there is
> nothing to prevent vcMinMagnitudeF from being supported for curly
> vectors. Whether it will produce a good looking result or not is
> another question.
>
> A work-around might be to use the "where" function, with your
> user-defined min_magnitude:
> u = where(sqrt(u*u + v * v) .lt. min_magnitude, u at _FillValue, u)
> v = where(sqrt(u*u + v * v) .lt. min_magnitude, v at _FillValue, v)
>
> before plotting. Let us know if you have problems getting this to work.
>
> I will create a ticket for implementing vcMinMagnitudeF for curly vectors.
>  -dave
>
>
>
>
> On Wed, Dec 10, 2014 at 7:50 AM, Kyle Griffin <ksgriffin2 at wisc.edu> wrote:
> > I'm not Dave, but I'll go ahead and say "no" - CurlyVectors are more
> akin to
> > streamlines in that they don't exist at any one "point" but rather get
> > longer and turn with the wind as magnitude increases. You can't simply
> turn
> > off the CurlyVector in some areas as it would break up the streamline by
> > falling below an arbitrary magnitude. vcMinMagnitude seems to look the
> best
> > with either LineArrow or FillArrow glyphs, in my experience.
> >
> > Good luck!
> >
> >
> > Kyle
> >
> > ----------------------------------------
> > Kyle S. Griffin
> > Department of Atmospheric and Oceanic Sciences
> > University of Wisconsin - Madison
> > Room 1421
> > 1225 W Dayton St, Madison, WI 53706
> > Email: ksgriffin2 at wisc.edu
> >
> > On Wed, Dec 10, 2014 at 7:04 AM, Xi Chang <xi.chang01 at gmail.com> wrote:
> >>
> >> Hi Dave, HI NCL,
> >>
> >> so, is there any way around how to use " res at vcMinMagnitudeF  " for
> >> "CurlyVector" mode?
> >> Thanks
> >>
> >> chang.
> >>
> >> On Fri, Nov 7, 2014 at 3:22 PM, David Brown <dbrown at ucar.edu> wrote:
> >>>
> >>> Try turning off the curly vectors. It's possible that it hasn't been
> >>> enabled for that glyph style.
> >>>  -Dave
> >>>
> >>>
> >>> On Friday, November 7, 2014, Xi Chang <xi.chang01 at gmail.com> wrote:
> >>>>
> >>>> Thanks Dave,
> >>>>
> >>>> Anyway, nothing happens when I did as follows (the results are still
> the
> >>>> same):
> >>>>
> >>>>   res at gsnScalarContour      = True              ; vectors over
> scalars
> >>>>   res at vcRefMagnitudeF       = 20.0              ; vec magnitude
> >>>>   res at vcRefLengthF          = 0.06              ; size of ref vector
> >>>>   res at vcLineArrowColor      = "black"           ; white vectors
> >>>>   res at vcMinDistanceF        = 0.025              ; thins arrows near
> >>>> pole
> >>>>   res at vcGlyphStyle          = "CurlyVector"     ; turns on curley
> >>>> vectors
> >>>>   res at vcMinMagnitudeF       = 5
> >>>>
> >>>> On Fri, Nov 7, 2014 at 12:25 AM, David Brown <dbrown at ucar.edu> wrote:
> >>>>>
> >>>>>
> >>>>>
> http://www.ncl.ucar.edu/Document/Graphics/Resources/vc.shtml#vcMinMagnitudeF
> >>>>>
> >>>>> On Thu, Nov 6, 2014 at 4:23 PM, Xi Chang <xi.chang01 at gmail.com>
> wrote:
> >>>>> > Hallo, is there any trick to display wind vectors only for those
> >>>>> > whose
> >>>>> > magnitude greater than XXX m/s, bellow this values are not plotted.
> >>>>> > Im using
> >>>>> > a function called gsn_csm_vector.
> >>>>> >
> >>>>> > Thanks
> >>>>> >
> >>>>> > _______________________________________________
> >>>>> > ncl-talk mailing list
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> >>>>> >
> >>>>
> >>>>
> >>
> >>
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> >
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