ODB(3L)                Senya Basin                        ODB(3L)



NAME   ODB - Ordinary Data Base - a simplified interface to NetCDF 



INTRODUCTION  

  The purpose of this library is to help users to get access to a data 
  stored in a popular data formats like NetCDF or HDF. Our objective was 
  to give a user the simplest interface we could think of as well as help 
  in maintaining some obvious data structures widely used in the 
  Oceanographic community. 

TWO SIMPLE EXAMPLES.

  Reading a NetCDF/HDF File.
  ==========================

  If you have a NetCDF(or HDF) file GCMoutput.cdf which has a variable 
  temp among others (like salt, vel, dens). 
  We will assume that you know the dimensions of temp 
  (NX = 360 and NY = 180) obtained by using ncdump for example. 

  The fragment of a Fortran code which does this will be the following: 

     dimension temp(360,180) 
  c.....................open a file 
     call odb_open  (idfile, 'GCMoutout.cdf', 0)  
  c.....................read the data for temperature
     call odb_rdvar (idfile, 'temp', temp)  
  c.....................close the file 
     call odb_close (idfile) 

  Writing a NetCDF File.
  ======================

  In order to make it easier for Fortran-programmers to understand 
  the usage of the ODB library we have included a Fortran fragment 
  which writes similar information, but in a form which is undocumented 
  as well as a machine-dependent binary. 

  Fortran Unformatted File:                       NetCDF File:
  parameter(MX=45, MY=32, MT=12)    parameter (MX=45,MY=32,MT=12)               
  real aa(MX,MY),                   real aa(MX,MY),                             
 *    xx(MX), yy(MY), tt(MT)       *    xx(MX),yy(MY),tt(MT)                   
                                                                              
  open (unit = 1, file = 'abc',     call odb_open (idf, 'abc', 1)               
 *     form = 'unformatted')                                                   
                                    call odb_wrdesc(idf, 'The Super-Duper GCM'//
                                   * 'Temperature; 0.0001 sec of run')         

  write (1) MX, MY, MT              call odb_setxyt(idf, 'longitude',MX,xx,     
                                   * 'latitude',MY,yy, 'Time',MT,tt, 'TEMP')   
  write (1) xx                                                                  
  write (1) yy                                                                  
  write (1) tt                                                                  
                                                                              
  do IT = 1, MT                     do IT = 1, MT                               
    call compute (MX, MY, IT, aa)     call compute (MX, MY, IT, aa)            
    write (1) aa                      call odb_wrxy (idf, IT, 'TEMP', aa)      
  enddo                             enddo                                       

  close (1)                         call odb_close (idf)                        


SYNOPSIS

 odb_open(idf, file, key) - opens a file 
   idf - /output/ integer variable used to store the file identifier 
   file - character string: file name 
   key - 0-read only, 1-update or create; 2-always re-create 
 odb_dfgr(idf, gname, nn) - defines a grid with a given name & dimension 
   idf - from previos call to odb_open 
   gname - character grid name (one word) 
   nn - grid's dimension (integer) 
 odb_dfvar?(idf, gn1, gn2, ... gnN, vname) - defines a variable based on a 
                                            specific set of grids 
   gn1...gnN - grid names from the previous call to odb_dfgr 
   vname - variable's name (one word) 
 odb_setxyt(idf,xunits,NX,xx,yunits,NY,yy,tunits,NT,tt,vname) - defines a 
                                       variable based on X,Y and T grids. 
   [x|y|t]units - units names for X, Y, and T grids 
   NX, NY, NT - number of points for X, Y, T grids 
   xx, yy, tt - arrays with values for X,Y and T grid data(real) 
   vname - variable's name (one word) 
 odb_wrgr(idf, gname, xx) - writes the gridpoints values to a NetCDF file. 
   gname - grid's name 
   xx - array with grid's data (real) 
 odb_wrvar(idf, vname, var) - writes the values of a variable to NetCDF file. 
   vname - variable's name 
   var - array of data (real by default.) 
 odb_rdgr(idf, gname, nx, xx) - reads the gridpoints values from a NetCDF file 
   gname - /input/ grid's name 
   nn - /output/ grid's dimension 
   xx - /output/ array with grid's data (real) 
 odb_rdvar(idf, vname, var) - reads the values of a variable 
   vname - variable's name 
   var - array to br filled by the data (real) 
 odb_set?attr(idf, vname, aname, val) - write an attribute for a variable 
   vname - variable's name 
   aname - attribute name 
   val - attribute value (if ? =c - character; =r real; =i integer; =d double) 
 odb_wrdesc(idf, desc) - write a description for the file 
   desc - description character string. 



COMPILATION

  If you are going to read or write/create a NetCDF files. 
  add the following libraries to your f77 options list: -lodb -lnetcdf -lsun 
  (Use -lodb -lnetcdfdf -ldf -lsun if you want to read HDF files as well). 

 Example: f77 -o abc abc.f -lodb -lnetcdf -lsun 



COMMENTS
      senya@rainbow.ldgo.columbia.edu  



                            Release 0.0.1         1993