Re: [Opengrads-devel] [Junk released by Allow List] Re: [Junk released by Allow List] Building GrADS v2 with new supplibs: first crack

[Arlindo da S. <da...@al...>]

On Feb 2, 2008 7:21 PM, Jennifer Adams <jm...@co...> wrote:

>
>
> Arlindo --
> There is a bug in seekgb.c of the g2clib that causes it to fail to detect
> the end of a grib2 record if sizeof(g2int) != 4 (i.e. on 64-bit systems).
> I guess we should put the patch in the subblib src files we are
> redistributing (on your site and COLA's). This bug causes gribmap to fail to
> find any records -- pretty bad.
>

OK, I'll patch it and check it in. Fell free to to checkout the supplib
sources and commit  but fixes like this one.

BTW, we autoconfiscated grib2c for easier integration in the supplibs; other
users of the library may appreciate this as well. We should contribute this,
along with your bug fix, to the 'upstream' maintainers. Are you in contact
with them?

Another important point. I need a small grib-2 file to add to the test
suite. Right now I have model.grb, model.nc and model.hdf - all the same
file, just in different formats.
(I test binary files by writing them out with 'fwrite' and then reading them
back.)
This allows me to apply the same test code to all of them. Ideally, one
should have a similar model.grb2 file.  Wes attempted to convert the
existing model.grb to grb 2 but wasn't able to because model.grb does not
conform to NCEP's tables, or some other obscure grib reason.


> The code path for hdf in sdfopen is new. I will look at it and see what's
> going wrong.
>

It would be good to have model_nc.ctl and model_hdf.ctl so I can test the
ctl interface for netcdf/hdf as well. If you contribute those 2 ctls I can
add the additional tests.


>
Where is model.hdf?
>

 When you checkout the sources look under pytests/data, all test data is
there.


> b) When using "set gxout fvwrite" to write binary files the missing value
> is not being written correctly, in either little-endian or big-endian mode.
> Is this a bug or a feature (I haven't verified whether v1.9 does the
> same)?
>
> Can you be more specific about what 'not being written correctly' means?
> Can you give me a script segment that shows what it is doing wrong? Undef
> handling in v2 is entirely different than 1.9 -- it won't help to look
> back.
>

The undef value is 1E+20 for the opened file (model.nc). I then use fwrite
to write all vars, levels, times, to disk. When I read it back a different
value is used for UNDEF:
2.2616e+06. Here is how to reproduce the error outside the testing
framework.  From the Unix command line:

- check out grads sources and go to the testing directory:

% cd grads/pytests

- Convince yourself that undef of input file is 1e+20

% ncdump data/model.nc

- Now convert model.nc to binary using 'fwrite'

% mkdir output
% ./lats4d -i model/model.nc -o output/stream -format stream -be -v

(or write a simple script to do just that; choose a variable with undefs,
like "ua").

- use stream.ctl to read file output/stream.bin that you just created. You
can either open this file in GrADS or use lats4d again for a quick summary:

% ./lats4d -i stream.ctl -format stats

...
     Name    Lev         Min         Max        MEAN        STDV         RMS
  --------- ---- ----------- ----------- ----------- ----------- -----------
  ua        1000    -12.9719  2.2616e+06  1.1868e+06  1.1296e+06  1.6383e+06
  ua         850    -22.5107  2.2616e+06  3.0661e+05  7.7434e+05  8.3272e+05
  ua         700    -19.0453  2.2616e+06  1.4750e+05  5.5850e+05  5.7757e+05
  ua         500    -26.0697  2.2616e+06   2055.4200  6.8046e+04  6.8067e+04
  ua         300    -30.2449     73.7551     12.3418     16.0524     20.2466
  ua         200    -18.9862     81.0138     14.3248     16.6574     21.9678
  ua         100    -19.2900     53.7100     11.3787     12.8745     17.1807
  --------- ---- ----------- ----------- ----------- ----------- -----------
+ ua           7    -30.2449  2.2616e+06  2.3472e+05  3.6177e+05  7.2858e+05

The maximum value is what was mistakenly written for UNDEF. Incidentally,
this problem does not happens with model.grb:

% ./lats4d -i model/model.ctl -o output/stream -format stream -be -v
% ./lats4d -i stream.ctl -format stats

...
    Name    Lev         Min         Max        MEAN        STDV         RMS
  --------- ---- ----------- ----------- ----------- ----------- -----------
  ua        1000    -12.9719     20.0281     -0.5000      6.5431      6.5601
  ua         850    -22.5107     29.7393      1.6346      8.3796      8.5361
  ua         700    -19.0453     33.9547      3.8051      9.2721     10.0211
  ua         500    -26.0697     50.9303      6.8472     11.9436     13.7655
  ua         300    -30.2449     73.7551     12.3418     16.0524     20.2466
  ua         200    -18.9862     81.0138     14.3248     16.6574     21.9678
  ua         100    -19.2900     53.7100     11.3787     12.8745     17.1807
  --------- ---- ----------- ----------- ----------- ----------- -----------
+ ua           7    -30.2449     81.0138      7.1189     11.9898     15.0878

   The test that is failing writes each input file to disk, and reads it
back checking each variable/level/time.

   Let me know if you have any questions.

       Arlindo

-- 
Arlindo da Silva
da...@al...