Thanks a lot Antonio !
It gives me a good example of using "section" and "logicalsection"
attributes.
Regards
Vincent
Le 21/12/2016 à 19:49, Antonio S. Cofiño a écrit :
Vincent,
I'm attaching a tile aggregation where the lon coordinate, and the
respective data array, are changed from 0 360 range to -180 180.
Best regards
Antonio
--
Antonio S. Cofiño
Associate Professor and Researcher
Grupo de Meteorología de Santander
Dep. of Applied Mathematics and Computer Sciences
Universidad de Cantabria (Spain)
Academic Visitor
National Centre for Atmospheric Science
Department of Meteorology
School of Mathematical, Physical and Computational Sciences
University of Reading (UK)
http://antonio.cofino.es
On 21/12/16 14:56, Vincent THIERION wrote:
I well undertand the benefit of virtual datasets.
Even I chose a physical aggregation, do you think, it's possible to
send / show me a NCML example of tiled aggregation you made ?
Regards
Vincent
Le 21/12/2016 à 15:40, Antonio S. Cofiño a écrit :
Yes, if you have already a clear data structure it's better to
persist the view as an physical case.
In my case I have some dataset defined in longitude from -180 to
180, but some users want it from 0 to 360 ... then I create a
virtual dataset, with 2 logical views from the data and one tiled
aggregation of them. This provided to me 2 views served from TDS but
from the same physical dataset without replication.
Regards
Antonio
On 21/12/16 14:25, Vincent THIERION wrote:
Antonio,
Thank you for your answer.
I think my best option is to stich / spatially aggregate individual
files (not virtually) and serve the aggregated image with TDS.
Vincent
Le 21/12/2016 à 11:22, Antonio S. Cofiño a écrit :
Vicent,
On 21/12/16 08:58, Vincent THIERION wrote:
Hello,
By reading different posts on tiled aggregation (i.e. aggregation
along longitude and latitude dimensions), such as :
*
http://www.unidata.ucar.edu/mailing_lists/archives/thredds/2011/msg00270.html
*
http://www.unidata.ucar.edu/mailing_lists/archives/thredds/2013/msg00500.html
better than "labor-intensive" NCML implementation it looks like
this capability is handled by GridDataset and the Netcdf
SubsetService object :
http://www.unidata.ucar.edu/mailing_lists/archives/netcdfgroup/2011/msg00133.html,
only accessible with java library while I work with the python
library.
All these posts are quite old and I ask me what the better way is
now ? Maybe stich all the netcdf files in one NetCDF before serve
on TDS ?
The tiled aggregation it's one problem and subsetting is different
one. To aggregate on non-outer dimensions the only existing in
netcdf-java it's tiled one. Never released with full support but
it's there and working. The most common cases are aggregation on
outer-dimensions or non-existing ones.
This aggregation could be made using netcdf-java ncml and serving,
using TDS, as opendap/netcdfsubsetting endpoints.
To subsetting dataset (aggregated on non-aggregated) relies on
tool/client side. Python pyDap or Netcd4 packages are able to
access opendap services to subsetting purposes. Please note that
the Netcdf4 package needs to access to netcdf library compiled
with opendap reading capabilities.
Only specific implementation like x-array python packages has some
multifile aggregation
http://xarray.pydata.org/en/stable/generated/xarray.open_mfdataset.html#xarray.open_mfdataset
NcML aggregation is general specification but only netcdf-java has
full support of it. Some other implemetations exist:
https://github.com/axiom-data-science/pyncml
or the BES implemetation:
http://docs.opendap.org/index.php/BES_-_Modules_-_NcML_Module
But neither of them supports Tiled aggregation.
Regards
Antonio S. Cofiño
Thank you for your useful feedbacks
--
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vincent.thierion [at] inra.fr
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Vincent THIERION
Ingénieur de recherche - THEIA - CES OSO
vincent.thierion [at] cesbio.cnes.fr
vincent.thierion [at] inra.fr
T. +33.(0)5.61.55.85.34
-https://dynafor.toulouse.inra.fr/dynafornet/index.php/fre/Collaborateurs/Permanents/Thierion
CESBIO (Bureau 123)
(UMR 5126 CNRS/CNES/UPS/IRD)
Bpi 2801
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31401 TOULOUSE CEDEX 9
INRA - Toulouse - Dynafor
(UMR 1201 INRA/INP-ENSAT/INP-EI Purpan)
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Auzeville BP 52627
31326 CASTANET-TOLOSAN CEDEX
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-------------------------------
Vincent THIERION
Ingénieur de recherche - THEIA - CES OSO
vincent.thierion [at] cesbio.cnes.fr
vincent.thierion [at] inra.fr
T. +33.(0)5.61.55.85.34 -
https://dynafor.toulouse.inra.fr/dynafornet/index.php/fre/Collaborateurs/Permanents/Thierion
CESBIO (Bureau 123)
(UMR 5126 CNRS/CNES/UPS/IRD)
Bpi 2801
18 Av. Edouard BELIN
31401 TOULOUSE CEDEX 9
INRA - Toulouse - Dynafor
(UMR 1201 INRA/INP-ENSAT/INP-EI Purpan)
24 chemin de Borde-Rouge
Auzeville BP 52627
31326 CASTANET-TOLOSAN CEDEX
-------------------------------
