Re: [netcdfgroup] reading variable dimension using fortran 90

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: Re: [netcdfgroup] reading variable dimension using fortran 90
• From: Dave Allured <dave.allured@xxxxxxxx>
• Date: Sat, 12 Jun 2010 11:44:18 -0600

Sudheer,

--Dave

On 6/10/2010 10:36 PM, Sudheer Joseph wrote:

Thank you Dave,
                                   The subroutine you mentioned is very
useful. But my question was slightly different. suppose if you get the
dimension size before reading the 3 dimensional variable. we cannot
use that information to read the netcdf 3rd dimension at a stretch.
I mean
if I use the

NTIM= nf_get_dim(time) ( just for illustration sake )
and use this for allocating the dimension for 3D variable it will not
accept as it is not defined as a parameter.

allocate(pres_in(NLONS, NLATS, NTIM))
count = (/ NLONS, NLATS,NTIM/)
start = (/ 1, 1, 1/)

One possibility came to my mind yesterday night was  to read the data
as xy slabs and use a do loop to read the time dimension. It appears
there is no way to read the 3D variable at one call if we are not
defining the dimension as parameter.
with best regards,
Sudheer

On Fri, Jun 11, 2010 at 3:42 AM, Dave Allured<dave.allured@xxxxxxxx>  wrote:

Sudheer,

If the names of the dimensions are always the same, then use
nf90_inq_dimid followed by nf90_inquire_dimension to get the length
of each dimension.  See the example on this page:

http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-f90/NF90_005fINQUIRE_005fDIMENSION.html

If all the dimensions have coordinate variables, then the following
subroutine will get several dimension lengths in one call:

http://www.esrl.noaa.gov/psd/people/dave.allured/data/f90/lib/getnc_dims.f90

If the dimension names change between Netcdf files, then the problem
is more complicated.  We can address that if neither of the above
works for you.

--Dave A.
NOAA/PSD/CIRES

On 6/10/2010 7:55 AM, Sudheer Joseph wrote:

Dear Users,
                       I have been coding a program to read multiple
netcdf files having different time dimensions. I want to know if there
is a way to read netcdf varibale with out defining the dimension as
parameter. with in fortran 90 program.
normally we need to define like below
   ! timesteps of data.
         integer, parameter :: NDIMS = 3, NRECS =1
         integer, parameter :: NTIM=1464, NLATS = 94, NLONS = 192
   allocate(pres_in(NLONS, NLATS, NTIM))count = (/ NLONS, NLATS,NTIM/)
         start = (/ 1, 1, 1/)

         ! Read the surface pressure and temperature data from the file, one
         ! record at a time.
         call check( nf90_get_var(ncid, pres_varid, pres_in, start =
start,count = count) )

In my case ntim may be different for different files. I wanted to use
the reading part as a subroutine where ntim is provided as a variable
and passed to subroutine
but if I declare ntim as varible then netcdf gives an error.
If any one have a solution please help. I am not looking for solutions
like replacing the parameter statement using shell script and re
compiling it etc.

with best regards,
Sudheer

• References:
  • [netcdfgroup] reading variable dimension using fortran 90
    • From: Sudheer Joseph
  • Re: [netcdfgroup] reading variable dimension using fortran 90
    • From: Dave Allured
  • Re: [netcdfgroup] reading variable dimension using fortran 90
    • From: Sudheer Joseph