Re: Vector disposition

From: David Brown <dbrown_at_nyahnyahspammersnyahnyah>
Date: Thu Feb 14 2013 - 13:47:54 MST

Hi Yann,
I am not quite sure I understand this question. Are you talking about the placement of vectors relative to each other, or it is something about the shape of individual vectors.
If you set the vcMinDistanceF resource, NCL thins the vectors from the bottom left to the top right (assuming ascending coordinates). A vector is discarded if it is too close in the projected space
to vectors that have already been accepted. This method deliberately tries not to establish any pattern of rows or columns or diamond shape or whatever. It just tries to generate a more or less equally spaced set of vectors that are hopefully representative of the field.
If you want the vectors to appear in rows and columns then you should not set vcMinDistanceF. Instead if you need to thin them you should set a stride greater than 1 for the input U and V arrays.
Hope this helps. If I have not understood your question, can you post a plot (PNG preferred to keep the size down) that illustrates your problem?

On Feb 10, 2013, at 2:00 AM, Yann Bertrand wrote:

> Hello,
> I draw (wind) lineArrow vectors with gsn_csm_vector_scalar_map,
> and the disposition of the vectors change depending on the differents areas i'm dealing with.
> sometime they appear in "sqaure" shape :
> ==> ==>
> ==> ==>
> and sometimes in "diamond" shape :
> ==>
> ==> ==>
> ==>
> Is it possible to force one shape?
> Thanks in advance.
> Yann.
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Received on Thu Feb 14 13:48:26 2013

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