Re: [ferret_users] @FNR in 2D fills up x dimension first

[Hella Riede <Hella.Riede@xxxxxx>]

Oops, pity.
Thank you for the reminder, Ansley!
 
 
 
Am 28.06.2018 um 18:31 schrieb Ansley C. Manke:
> Hi Hella,
>  
> Only a few of the transformations are calculated in multiple 
> dimensions.  Most apply the operation one direction at a time as you're 
> seeing here. For transformations in general 
> <../../documentation/users-guide/variables-xpressions/XPRESSIONS#GeneralInfo>, 
>
>  
>    /Transformations are normally computed axis by axis; if multiple
>    axes have transformations specified simultaneously (e.g.,
>    //U[Z=@AVE,L=@SBX:10]//) the transformations will be applied
>    sequentially in the order X then Y then Z then T.//...
>    /
>  
> only averages and definite integrals are computed using multiple 
> dimensions, as they involve area calculations, and NGD and NBD also 
> count over all dimensions given.  So yes, the filling transformations 
> fill in X then in Y, etc.
>  
> Ansley
>  
>  
> On 6/28/2018 7:37 AM, Hella Riede wrote:
> > Hello ferret community,
> >  
> > I am using @FNR in two dimensions and got an unexpected result (see 
> > ferret script at end of this mail):
> >  
> > In the attached ferret_before_FNR.png, the original 2D grid cells are 
> > shown (values inherited from dots by scat2grid, see below).
> >  
> > ferret_after_FNR.png shows the result after applying @FNR (fill with 
> > nearest neighbor) in 2 dimensions.
> >  
> > As an example for the unexpected result, lets take the grid cell at 
> > (x=8,y=5). Its value before @FNR was undefined. The nearest neighbor 
> > is (x=8,y=8). Yet, the value is inherited from (x=2,y=4).
> >  
> > Is @FNR not supposed to be applied in 2D or is the logic behind 
> > different from what I expected? It seems the missing points are always 
> > filled up in x dimension first, and only remaining missing values are 
> > then filled up in y direction ...
> >  
> > I attached a manual version of what I would have expected as 
> > ferret_FNR_expected.png.
> >  
> >  
> > Thank you very much in advance for helping to clarify this.
> >  
> >  
> > Best regards,
> > Hella Riede
> >  
> >  
> >  
> >  
> > can var/all
> > can sym/all
> >  
> > let a   = {1,1,8,8,2}
> > let b   = {1,8,8,1,4}
> > let val = {2,4,6,8,10}
> >  
> > def ax/x=1:8:1 xax
> > def ax/y=1:8:1 yax
> >  
> > def sym lev = (1.5,10.5,1)
> >  
> > !! assign values from dots to grid cells
> > set win 1
> > let gridded = 
> > SCAT2GRIDGAUSS_XY(a,b,val,x[gx=xax],y[gy=yax],0.8,0.8,0.8,0)
> > shade/lev=($lev) gridded
> > !! plot original scattered values for comparison
> > go polymark poly/lev=($lev)/key/ov/line/fill a b val circle 2
> >  
> >  
> > !! fill up undefined values with nearest neighbor
> > set win 2
> > let nn = gridded[x=@FNR,y=@FNR]
> > shade/lev=($lev) nn
> > go polymark poly/lev=($lev)/key/ov/line/fill a b val circle 2
> >