Re: missing values with month_to_seasonN

From: Will Hobbs <whobbs_at_nyahnyahspammersnyahnyah>
Date: Thu, 06 Sep 2007 15:09:28 PDT

('binary' encoding is not supported, stored as-is) Adam

Just to clarify what the correct behavior should be in the 'fixed'
version, will it

1) Pass the _FillValue attribute from the input array to the output
array, and set missing values in the output to that value

or

2) Set the _FillValue attribute in the output array to the default (i.e.
-999.) ?

Will

On Thu, 06 Sep 2007 15:57:30 -0600 Adam Phillips wrote:

> Hi Will,
>
> I just created a test script looking into this and you're correct,
> month_to_seasonN is labeling missing data as -999 but leaves the
> _FillValue attribute the same as whatever it was when it was passed in
> to the function... This is of course wrong, and will be fixed upon the
> next release of NCL.. If anyone needs a corrected version of this
> function let me know...
>
> Thanks for pointing this out.
> Adam
>
> Will Hobbs wrote:
> > Hi all
> >
> > This is just a comment on a problem that I'm having with the
> > month_to_seasonN function. It may affect other functions but this is the
> > first time I've come across it.
> >
> > I'm using SST from the hadisst dataset, which uses a _FillValue of
> 1e+20,
> > including land surface areas. See the following snippet, with
> comments....
> >
> > x = f1->sst
> >
> > print(x@_FillValue) ;correctly returns 1+e20
> > print(num(ismissing(x))) ; if the data includes land surface, this
> > must be non-zero
> >
> > xSeas = month_to_seasonN(x, season)
> >
> > print(xSeas@_FillValue) ;returns 1+e20. fine
> >
> > print(num(ismissing(xSeas))) ;returns 0, wrong!
> >
> > print(num(xSeas.eq.xSeas@_FillValue)) ;again, incorrectly returns 0
> >
> > print(num(xSeas.eq.-999.)) ;returns a sensible answer
> >
> > Of course it's easy enough to fix a workaround for this..
> >
> > xSeas@_FillValue = -999.
> >
> > ...but if you're not aware of this it can cause some unusual results
> > further down the line.
> >
> > Will
> >
> >
> >
> > ============================
> > Will Hobbs
> > PhD Candidate
> > Room A113
> > UCLA Department of Geography
> > 1255 Bunche Hall
> > Los Angeles CA 90095-1524
> > Tel: 310 663 2631
> >
> >
> > _______________________________________________
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> > ncl-talk_at_ucar.edu
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>
> --
> --------------------------------------------------------------
> Adam Phillips asphilli_at_ucar.edu
> National Center for Atmospheric Research tel: (303) 497-1726
> ESSL/CGD/CAS fax: (303) 497-1333
> P.O. Box 3000
> Boulder, CO 80307-3000 http://www.cgd.ucar.edu/cas/asphilli

============================
Will Hobbs
PhD Candidate
Room A113
UCLA Department of Geography
1255 Bunche Hall
Los Angeles CA 90095-1524
Tel: 310 663 2631

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Received on Thu Sep 06 2007 - 16:09:28 MDT