Re: re-converting 1D to 3D array.

Hi,

 And thanks for the quick reply. However, based on your answer,
this assumes that the pr variable in the NetCDF file is originally in (time,
lat, lon) dimensions correct? It is in (time, xc, yc) coordinate, so is
there an maneuver to get around this?

Sho

On Tue, Mar 9, 2010 at 6:46 PM, Dave Allured <dave.allured@noaa.gov> wrote:

> Sho Kawazoe,
>
> This is the second statement in your program:
>
> prc = fin->pr
>
> Move up the four lines for lat1, lat2, lon1, lon2; and try this instead:
>
> prc = fin->pr(:,{lon1:lon2},{lat1:lat2})
>
> printVarSummary(prc)
> print(prc&lon)
> print(prc&lat)
> exit
>
> If latitudes in the file go from high to low, then reverse the order
> of lat1 and lat2 above. Same for longitudes.
>
> Somehow you started making this reader more complicated than it
> should be. This should work better. We do not need to discuss
> conversion of dimensions unless your problem is more complicated
> than it looks.
>
> --Dave A.
> NOAA/PSD/CIRES
>
> Sho Kawazoe wrote:
> > NCL users,
> >
> > I'm still very raw in my knowledge with ncl, and was wondering if anyone
> > can help me out.
> >
> > I'm currently using precipitation data with MM5 (from EGS), and trying to
> > mask a specific lat and lon point, with the ultimate purpose of
> outputting
> > data within that specific grid, and truncating the data to where when I
> end
> > up concatenating other files, I am well below the 2gb threshold.
> >
> > Steps leading to retrieving the desiredvalues in 1D looks fine, and the
> > output file is well below the original input file size. However, when I
> > reconvert the 1D to 3D, the file is back to the same size as the input
> file,
> > and it looks like missing values are inputted into the output file, which
> > doesn't make the file any smaller.
> >
> > Is there a way to reconvert the 1D array to 3D array and keep only the
> > precip values we want, without the missing values(keep in mind that the
> > associated metadata needs to be there as well)? A simple onedtond doesn't
> > look like the solution, and I'm misunderstanding the coding.
> >
> > The script is as follows. Any help is appreciated.
> >
> > ;*****************************************************
> > ; Read original NetCDF file.
> > ;*****************************************************
> >
> > fin = addfile ("pr_MM5I_1979010103.nc","r")
> >
> > ;******************************************************
> > ; Upload netCDF file variables, set dimensions
> > ;******************************************************
> >
> > prc = fin->pr ; obtain pr(time,xc,yc) values. Dimension is
> in
> > 3D
> > lat = fin->lat
> > lon = fin->lon
> > time = fin->time
> > Lambert_Conformal = fin->Lambert_Conformal
> >
> > dim = dimsizes(prc)
> > ntime = dim(0)
> > nlat = dim(1)
> > nlon = dim(2)
> >
> > latlonmask2 = prc(:,:,:) ; assign dim size to masking var
> > latlonmask2 = 0 ; initialization
> >
> > ;**************************************************************
> > ; Indicate coordiate you want to analyze. Make sure you
> > ; check the NetCDF file for correct lat lon specification!!
> > ;
> > ; Mask through time, xc, and yc for entire precip variable to
> > ; analyze specifc regions
> > ;**************************************************************
> >
> > lat1 = 37
> > lat2 = 47
> > lon1 = 269
> > lon2 = 279
> >
> > do k = 1, ntime-1
> > do j = 1, nlat-1
> > do i = 1, nlon-1
> > if (lat(j,i).ge.lat1 .and. lat(j,i).lt.lat2 .and. lon(j,i).gt.lon1
> > .and. lon(j,i).le.lon2) then
> > latlonmask2(k,j,i) = 1
> > end if
> > end do
> > end do
> > end do
> >
> > desiredvalues = mask(prc, latlonmask2, 1)
> >
> > ;********************************************************************
> > ; Convert the masked region to a 1d array, which allows us to then
> > ; use the ncl function "ind" to keep only the data from the region
> > ; we are interested in looking at. This also keeps all the
> > ; metadata associated with each precip value.
> > ;*******************************************************************
> >
> > desired1d = ndtooned (desiredvalues) ; convert to 1d array
> > indices = ind (.not.ismissing(desired1d)) ; keep precip values that
> > have no missing data.
> > output1d = desired1d(indices) ; all non-missing values
> > desiredvalues = onedtond(output1d,dimsizes(desiredvalues))
> > delete (desired1d) ; clean up if you wish.
> > delete (indices)
> >
> > ;******************************************************************
> > ; Create a new nc output file
> > ;******************************************************************
> >
> > system("/bin/rm -f region_output.nc") ; remove any
> pre-existing
> > file
> > fout = addfile("region_output.nc","c")
> > filedimdef(fout,"time",-1,True) ; Makes time an UNLIMITED
> > dimension (as suggested by NCL)
> >
> > fout->prc = output1d
> >
> > fout->lat = lat
> > fout->lon = lon
> >
> > end
> >
> >
> > ------------------------------------------------------------------------
> >
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-- 
Sho Kawazoe
Helser Livingston Community Advisor
Graduate Student Meteorology
Home Address
    3701 Helser Livingston
    Ames, IA 50012
Office Address
    2027 Agronomy
    Ames, IA 50010
Iowa State University
shomtm62@iastate.edu
Room: 515-572-2731

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Received on Wed Mar 10 12:32:31 2010