Access data files in aggregation

[Jennifer Adams]

Tony,
A 'dtype netcdf' descriptor file is not well-suited for OPeNDAP data  
sets. When you use the sdf/open/xdfopen commands, the I/O is done once  
for the entire requested grid; whereas with the open command and a  
dtype netcdf descriptor, the I/O is done row-by-row. If the data is on  
a server, using 'dtype netcdf' means you have to hit the server  
multiple times and it's much to slow.  The way to do it is with XDFOPEN  
-- just the first two lines of your descriptor file should be enough.
Jennifer


On Apr 20, 2005, at 4:41 AM, Tony Jolibois wrote:

>         Jennifer,
>
>  It doesn't work via http.
>  Here is my descriptor file :
>
> DSET  
> http://opendap-old.mercator-ocean.fr/data/mercator_psy2v1_mersea/med/ 
> %y4%m2%d2.nc
>  OPTIONS template
>  XDEF 341 LINEAR -6 0.125
>  YDEF 129 LINEAR 30 0.125
>  ZDEF 8  LEVELS  5 30 50 100 200 500 1000 2000
>  TDEF 588 LINEAR 22may2003 1dy
>  UNDEF 1.e+35 _FillValue
>  DTYPE netcdf
>  VARS 12
>  temperature 8 z,y,x temperature [degC]
>  salinity 8 z,y,x  salinity
>  u 8 z,y,x zonal velocity [m/s]
>  v 8 z,y,x meridian velocity [m/s]
>  ssh 0 y,x ssh [m]
>  mld 0 y,x mld [m]
>  mlp 0 y,x mlp [m]
>  bsfd 0 y,x bsfd [m3/s]
>  taux 0 y,x taux [Pa]
>  tauy 0 y,x tauy [Pa]
>  qtot 0 y,x qtot [W/m2]
>  emp 0 y,x water flux [Kg/m2/s]
>  ENDVARS
>
>  With this one I can not display the data.
>
>  If I put : DSET  
> /data/mercator/data/mercator_psy2v1_mersea/med/%y4%m2%d2.nc
>  then it works.
>
>  What is my error ?
>  Regards,
>  Tony
>
>  Jennifer Adams wrote:
>
> Try using xdfopen with a brief descriptor file, which should include
>  the dset entry you've described and 'options template'.  --Jennifer
>
>
>  On Apr 19, 2005, at 10:11 AM, Tony Jolibois wrote:
>
>
>           Hi all,
>
>  Is it possible to access data files via http in a data descriptor file
>  ?
>  e.g
>
>  DSET http://...../%y4%m2%d2.nc
>  ...
>
>  instead of DSET /home/grads/data/%y4%m2%d2.nc
>
>  Thanks in advance,
>  Tony
>
>
>
>
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