Re: Reading a vector of points all at once

Ummm,

Yes, I guess to get a the value of 'u' at the 4 locations
then a do loop is necessary.

I think the NCL is essentially giving you a 2D array
consisting of ....

   5,10 5,44 5,73 5,20
  87,10 87,44 87,83 87,20
  20,10 20,44 20,83 20,20
  15,10 15,44 15,83 15,20

I think that one of the core developers will have to address this.

D

On 10/21/2011 09:51 AM, Hahmann, Andrea N. wrote:
> Hi Dennis
>
> To my surprise the example I gave does work without a loop but the results
> are not what I expected... Here is the simple example and the results.
>
> begin
> inear = (/5,87,20,15/)
> jnear = (/10,44,73,20/)
>
> ff = addfile("/mnt/mimer/ahah/SBaltic/wrfout_d02_2010-10-30_00.nc","r")
> u = new(dimsizes(inear),"float")
> do k=0,dimsizes(inear)-1
> u(k) = ff->U(0,0,inear(k),jnear(k))
> end do
> printVarSummary(u)
>
> delete(u)
> u = ff->U(0,0,inear,jnear)
> printVarSummary(u)
> end
>
>
> The result for the first is a 1-D array, but a 2D array (4 x 4) from the
> second!
>
> Variable: u
> Type: float
> Total Size: 16 bytes
> 4 values
> Number of Dimensions: 1
> Dimensions and sizes: [4]
> Coordinates:
> Number Of Attributes: 7
> coordinates : XLONG_U XLAT_U
> stagger : X
> units : m s-1
> description : x-wind component
> MemoryOrder : XYZ
> FieldType : 104
> _FillValue : 9.96921e+36
>
> Variable: u
> Type: float
> Total Size: 64 bytes
> 16 values
> Number of Dimensions: 2
> Dimensions and sizes: [south_north | 4] x [west_east_stag | 4]
> Coordinates:
> Number Of Attributes: 6
> FieldType : 104
> MemoryOrder : XYZ
> description : x-wind component
> units : m s-1
> stagger : X
> coordinates : XLONG_U XLAT_U
>
>
>
>
>
>
> ----
> Andrea N. Hahmann
> Senior Scientist
> Wind Energy Division
> Risø DTU
>
> Technical University of Denmark
> Risø National Laboratory for Sustainable Energy
> Frederikborgvej 399, P.O. Box 49
> 4000 Roskilde, Denmark
>
> Direct +45 4677 5471
> Mobil: +45 2133 0550
> ahah@risoe.dtu.dk
> http://www.risoe.dtu.dk
>
>
>
>
> On 10/20/11 7:31 PM, "Dennis Shea"<shea@ucar.edu> wrote:
>
>> I think the following will work:
>>
>> inear = (/5,87,20,15/)
>> jnear = (/10,44,73,20/)
>> u = ff->U(inear,jnear)
>> printVarSummary(u)
>>
>> On 10/20/11 7:19 AM, Hahmann, Andrea N. wrote:
>>> Good morning
>>>
>>> I have a not so small list of grid points I would like to read from a
>>> NetCDF file. Here is an example (ff is an open file):
>>>
>>> begin
>>> inear = (/5,87,20,15/)
>>> jnear = (/10,44,73,20/)
>>>
>>> u = new(dimsizes(inear),"float")
>>> do k=0,dimsizes(inear)-1
>>> u(k) = ff->U(inear(k),jnear(k))
>>> end do
>>> end
>>>
>>> Can this be rewritten without using the loop over the grid point? A
>>> similar loop seems to be slowing my script down and I have a lot of
>>> files to readŠ
>>>
>>> Thanks,
>>> Andrea
>>>
>>> ----
>>> Andrea N. Hahmann
>>> Senior Scientist
>>> Wind Energy Division
>>> Risø DTU
>>>
>>> Technical University of Denmark
>>> Risø National Laboratory for Sustainable Energy
>>> Frederikborgvej 399, P.O. Box 49
>>> 4000 Roskilde, Denmark
>>>
>>> Direct +45 4677 5471
>>> Mobil: +45 2133 0550
>>> ahah@risoe.dtu.dk
>>> http://www.risoe.dtu.dk
>>> _______________________________________________
>>> ncl-talk mailing list
>>> List instructions, subscriber options, unsubscribe:
>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk

-- 
======================================================
Dennis J. Shea                  tel: 303-497-1361    |
P.O. Box 3000                   fax: 303-497-1333    |
Climate Analysis Section                             |
Climate & Global Dynamics Div.                       |
National Center for Atmospheric Research             |
Boulder, CO  80307                                   |
USA                        email: shea 'at' ucar.edu |
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