Re: Speed difference

To update everyone, this was solved offline. Adrien wished to map 3D
(time,lat,lon) data onto a 2D (coordinate,time) array.. The easiest way
to handle this was to use coordinate subscripting:

begin
     latlon = asciiread("gridout.cru.data",(/67420,2/),"float")
     lat = latlon(:,1)
     lon = latlon(:,0)

     a = addfile("interp_tas.nc","r")
     tmp1 = a->sfct(0:1199,:,:) ; I've just take the 100 first years

     intmp=new((/67420,1200/),float)
     do ipt=0,5 ;67420-1
        printVarSummary(tmp1(:,{lat(ipt)},{lon(ipt)}))
        print("lat(ipt)= "+lat(ipt)+", lon(ipt)= "+lon(ipt))
        intmp(ipt,:) = (/ tmp1(:,{lat(ipt)},{lon(ipt)}) /)
     end do
end

Adrien Mauss wrote:
> Hello everyone !
>
> I have got some strange things about a part of a program. I need to pick terrestrial data from a global grid (720,360). For a first file which contains some 102 years,
> this part is very fast (1-2 min) whereas when I use an other file of 130 years, it takes more than 2-3 hours. So I've tried each one with 100 years, the difference of
> speed is the same. I've looked for the origins and finally, I've found the part which was so long. Here the minimum script which shows the problem :
>
>
> "begin
>
> latlon = asciiread("/Users/adrien/data/PARAMETERS/gridout.cru.data",(/67420,2/),"float") ; loading the grid of terrestrial points
> lat = latlon(:,1)
> lon = latlon(:,0)
> print("grid data read")
>
> print("TMP")
> a = addfile("/Users/adrien/data/INPUT/cru_ts_2_10.1901-2002.tmp.nc","r") ; loading the temperature for the global grid
> tmp1 = a->tmp(0:1199,:,:) ; I've just take the 100 first years
>
> latit = a->lat ; latitude and longitude
> longit = a->lon
>
> tmp2=(/tmp1(:,ind(latit.eq.lat(0)),ind(longit.eq.lon(0)))/)
> ;tmp2=fspan(0.,1199.,1200)
> printVarSummary(tmp2)
>
> intmp=new((/67420,1200/),float)
> do ipt=0,67420-1
> ;intmp(ipt,:)=tmp1(:,ind(latit.eq.lat(ipt)),ind(longit.eq.lon(ipt))) ; the initial command
> ;tmp2=tmp1(:,ind(latit.eq.lat(ipt)),ind(longit.eq.lon(ipt))) ; first part : picking the temperature of the point ; alone this command is very fast
> intmp(ipt,:)=(/tmp2/) ; second part : WHERE I LOOSE ALL THE SPEED
> print("tmp : "+ipt) ; in order to see the speed
> end do
>
> end"
>
> Variable: tmp2
> Type: float
> Total Size: 4800 bytes
> 1200 values
> Number of Dimensions: 1
> Dimensions and sizes: [1200]
> Coordinates:
> Number Of Attributes: 1
> _FillValue : 1e+20
>
>
> So the problem appears when I assign all the values to one point (lat,lon) even if I use a constant vector from the first point. But when I'm using a other vector
> (fspan(1.,1199.,1200)) of same size and same type (float) as it's shown by printVarSummary(), it's becoming faster (>50 times faster). I was thinking every float
> vector would have a same "behavior". I can't understand why the treatment is not the same one. Perhaps, I did something wrong. If somebody has a gimmick to
> make it faster. I can wait but I will be using it 4 times in the program, and I should use the program more than 50 times, so it would be better to have something
> fast...
>
> Thanks
>
> Adrien Mauss
> mauss_at_wisc.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
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