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Re: NetCDF and DDI -- file format

Hi Mike,

>       Hello, again.  I was a little unsure of the procedure you suggested
> in your e-mail reponse.  I realize that I need to write a fortran program
> to read in the data from my data files ( easily done ) and then create
> another data file in NetCDF format. You said to follow NetCDF form, using
> the interfaces in the netCDF library.  I am not sure what library or
> interfaces you are referring to.  Is it somewhere explained how this
> NetCDF format works so that I know what commands to put into my fortran
> program in order to rearranged the data into NetCDF format?  I know, for
> instance, that our current data files are read in using status='old',
> form='unformatted', access='direct', and recl=7840 and the following read
> statement: READ (101,REC=1) ((X(LAT,LON),LON=1,49),LAT=1,40).  Are there
> any such commands which I need to use when outputting into the new file?

Yes, the netCDF data model, Fortran and C library interfaces, and format are
documented in the NetCDF Users Guide, which is available in either hard-copy
or on-line form.  The on-line documentation is best viewed with a WWW
browser such as Netscape or Mosaic, aimed at the netCDF home page:

    http://www.unidata.ucar.edu/packages/netcdf/

where you will find links to a list of Frequently Asked Questions about
netCDF, on-line documentation, pointers to freely-available and commercial
software for manipulating or displaying netCDF data, information about the
netCDF mailing list, and indexed searches through information about netCDF.

I've appended a short example Fortran program contributed by a netCDF user
that might give you the flavor of the netCDF interface, but to use the
netCDF library in a program you will probably need to consult the Users
Guide.  A PostScript version is available via anonymous FTP from

    ftp://ftp.unidata.ucar.edu/pub/netcdf/guide.ps.Z

but we would be happy to mail you a printed copy if you supply your mailing
address.

______________________________________________________________________________

Russ Rew                                           UCAR Unidata Program
address@hidden                              http://www.unidata.ucar.edu


      PROGRAM wrt_ncdf

C Simple example from Jeremy Kepner <address@hidden>

       IMPLICIT NONE

       INCLUDE '/usr/local/include/netcdf.inc'

       INTEGER n_dim,x_dim,y_dim,z_dim
       PARAMETER(n_dim = 3, x_dim = 20, y_dim = 10, z_dim = 5)
       INTEGER dim_array(n_dim)
       INTEGER start(n_dim),count(n_dim)

       INTEGER ncid, errcode
       INTEGER x_id,y_id,z_id,arr_id
       REAL array(x_dim,y_dim,z_dim)
       INTEGER i,j,k

C      Put something into the array.
       DO i=1,x_dim
       DO j=1,y_dim
       DO k=1,z_dim
         array(i,j,k) = (i-1) + x_dim*(j-1) + x_dim*y_dim*(k-1)
       ENDDO
       ENDDO
       ENDDO

C      Create netCDF file.
       ncid = NCCRE('test.nc', NCCLOB, errcode)

C      Create netCDF dimensions.
       x_id = NCDDEF(ncid, 'X', x_dim, errcode)
       y_id = NCDDEF(ncid, 'Y', y_dim, errcode)
       z_id = NCDDEF(ncid, 'Z', z_dim, errcode)

C      Create a netCDF variable.
C      Assign dimensions to array.
       dim_array(1) = z_id
       dim_array(2) = y_id
       dim_array(3) = x_id
       arr_id = NCVDEF(ncid,'array',NCFLOAT,n_dim,dim_array,errcode)

C      Skip attributes.

C      Leave definitions.
       CALL NCENDF(ncid, errcode)

C      Write variable to file.
       start(1) = 1
       start(2) = 1
       start(3) = 1
       count(1) = z_dim
       count(2) = y_dim
       count(3) = x_dim
       CALL NCVPT(ncid,arr_id,start,count,array,errcode)

C      Close the file.
       CALL NCCLOS(ncid, errcode)

      END