[ncl-talk] Trouble with masking data for new file

[Adam Phillips]

Hi Jonathan,
I think the issue is related to your last set of where calls:
cntrycodes_regionALL =
where(cntrycodes_region01.eq.1,1,cntrycodes_regionALL)
cntrycodes_regionALL =
where(cntrycodes_region02.eq.2,2,cntrycodes_regionALL)
cntrycodes_regionALL =
where(cntrycodes_region03.eq.3,3,cntrycodes_regionALL)

Running small tests here, each call is likely overwriting the
cntrycodes_regionALL array on each line. This is one of those situations
where the coding looks right (to me at least), but where is behaving
differently than I would expect. I think this has to do with how the where
function interprets areas set to _FillValue. Try changing the above lines
to this:
cntrycodes_regionALL =
where(ismissing(cntrycodes_regionALL).and.cntrycodes_region01.eq.1,1,cntrycodes_regionALL)
cntrycodes_regionALL =
where(ismissing(cntrycodes_regionALL).and.cntrycodes_region02.eq.2,2,cntrycodes_regionALL)
cntrycodes_regionALL =
where(ismissing(cntrycodes_regionALL).and.cntrycodes_region03.eq.3,3,cntrycodes_regionALL)
(and make sure cntrcodes_regionALL has a _FillValue attribute set)..

Let ncl-talk know if that doesn't work.
Adam




On Fri, Apr 16, 2021 at 9:05 AM Buzan, Jonathan via ncl-talk <
ncl-talk at mailman.ucar.edu> wrote:

> Hi NCL-Talk,
>
> I have something conceptually wrong in my head with NCL.
>
> I am attempting to take a .nc file with countries, and map them onto
> regions.
>
> Country Map
>
>
>
> I use:
>
> cntrycodes!0 = "lat"
> cntrycodes&lat = lat
> cntrycodes!1 = "lon"
> cntrycodes&lon = lon
> cntrycodes at long_name = "Country Codes"
> cntrycodes at missing_value = cntrycodes at _FillValue
> …
>
>
> cntrycodes_region04 = where(cntrycodes.eq.7,4,cntrycodes_region04)
> cntrycodes_region04 = where(cntrycodes.eq.10,4,cntrycodes_region04)
> cntrycodes_region04 = where(cntrycodes.eq.13,4,cntrycodes_region04)
> …
> cntrycodes_region04 = where(cntrycodes.eq.145,4,cntrycodes_region04)
> cntrycodes_region04 = where(cntrycodes.eq.152,4,cntrycodes_region04)
>
>
> I get:
>
> I do this for 16 regions.
> Then I try to put it together:
>
> cntrycodes_regionALL =
> where(cntrycodes_region01.eq.1,1,cntrycodes_regionALL)
> cntrycodes_regionALL =
> where(cntrycodes_region02.eq.2,2,cntrycodes_regionALL)
> cntrycodes_regionALL =
> where(cntrycodes_region03.eq.3,3,cntrycodes_regionALL)
> …
> cntrycodes_regionALL =
> where(cntrycodes_region15.eq.15,15,cntrycodes_regionALL)
> cntrycodes_regionALL =
> where(cntrycodes_region16.eq.16,16,cntrycodes_regionALL)
>
> And I get:
>
>
> I am not sure what I am doing wrong. But I have a feeling it is with how I
> am using the where function.
>
> Cheers,
> -Jonathan
>
>
>
>
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-- 
Adam Phillips
Associate Scientist,  Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/   303-497-1726

<http://www.cgd.ucar.edu/staff/asphilli>
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