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

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

Attachment: ferret_before_FNR.png
Description: PNG image

Attachment: ferret_after_FNR.png
Description: PNG image

Attachment: ferret_FNR_expected.png
Description: PNG image

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