Welcome to the ncio library.
Two example programs are avaiable to test the functionality of ncio:
test_ncio.f90 and pres_temp_4D_wr_compare.f90. These programs can be compiled using the Makefile and run from the command line (see below). The user may need to modify the Makefile so that the locations of the NetCDF library installed on their machine are properly referenced. These are currently defined as:
LIB = /opt/local/lib
INC = /opt/local/include
Find these lines in the Makefile and modify as needed.
make test
./test_ncio.x
This program is an example of how to simply write various size arrays and dimensions to an output netcdf file (out_ncio.nc). Generally the program writes checkerboard pattern data to the file highlighting different functionality of the ncio library.
make compare
./pres_temp_4D_wr.x
./pres_temp_4D_wr.x 10
This program is identical to the example code provided by Unidata pres_temp_4D_wr.f90, however it includes the same example using the ncio library, and using the ncio library and maintaining the NetCDF file open throughout the program via an ncid variable.
The comparison program can run multiple loops to test timing. In the above example, the first program call will run through the program and calculate the timing for 1 iteration, the second program call will calculate the timing for 10 iterations. A timing table is output at the end of the program.
**The NCIO API is properly documented in the GMDD manuscript found here, however a summary of the public functions available through the ncio module can be found below:
nc_read
nc_size
nc_read_attr
nc_create
nc_write_attr
nc_write_map
nc_write_dim
nc_write
nc_open
nc_close
The first two are useful for reading variable attributes and data from an existing NetCDF file. The remaining functions are used for creating and writing to NetCDF files.
subroutine nc_read(filename,dat,name,[start],[count],[missing value])filename name of the NetCDF data file to read from
dat Fortran data type into which data will be loaded
name name of the variable in NetCDF file to be read
start vector of values specifying starting indices for reading data from each dimension (optional)
count vector of values specifying how many values to read in each dimension (optional)
missing value Value to assign to missing data read from the file (optional)
function nc_size(filename,name,[ncid]) result(size)filename name of the NetCDF data file to read from
name name of the dimension variable in NetCDF file of which to determine size
size Integer size (length) of the dimension variable returned from the function
ncid File ID for a file that remains open for various NCIO calls (optional)
subroutine nc_read_attr(filename,[varname],name,value)filename name of the NetCDF data file to read from
varname name of the variable of interest (optional, if not given global a global attribute is expected).
name name of the variable or global attribute to be read
value character value of the attribute read from the file
ncid File ID for a file that remains open for various NCIO calls (optional)
subroutine nc_create(filename,[author],[creation\_date],[institution],[description])filename name of the NetCDF file to be created
author name of the author of the file (optional)
creation_date date of the file creation, string format (optional)
institution name of the author's institution (optional)
subroutine nc_write_attr(filename,[varname],name,value,[ncid])filename name of the NetCDF file in which to write attribute
varname name of the variable in which to write the attribute (optional)
name name of the attribute to be written
value value of the attribute to be written
ncid File ID for a file that remains open for various NCIO calls (optional)
subroutine nc_write_map(filename,name,[lambda],[phi],[x_e],[y_n],[ncid])filename name of the NetCDF file in which to write the grid map definition
name name of the grid mapping to be defined
lambda longitude of projection origin (optional)
phi latitude of projection origin (optional)
x_e false easting (optional)
y_n false northing (optional)
ncid File ID for a file that remains open for various NCIO calls (optional)
subroutine nc_write_dim(filename,name,[x],[dx],[nx],[long_name],[standard_name],[units],[axis],[calendar],[ncid])filename name of the NetCDF file in which to define dimension
name name of the dimension to be defined in NetCDF file
x Fortran data type (scalar or vector) specifying values of dimension. If nx is present and size(x)==1, x specifies the starting point of the dimension variable
dx distance between each dimension value (optional)
nx length of dimension variable (optional)
long_name NetCDF attribute, a long descriptive name of the variable (optional)
standard_name NetCDF attribute specifying the CF convention standard name of the variable (optional)
units NetCDF attribute of the units of the variable (optional)
axis NetCDF attribute of the standard axis of the variable (optional)
calendar NetCDF attribute of the calendar type to be used for time dimensions (optional)
ncid File ID for a file that remains open for various NCIO calls (optional)
subroutine nc_write(filename,name,dat,[dims],[dim1,...,dim6],[start],[count],[long_name],[standard_name],[grid_mapping],[units],[missing_value],[ncid])filename name of the NetCDF file in which to write data
name name of the variable in NetCDF file to be written
dat Fortran data type of data to be written
dims vector of dimension names of the variable in NetCDF file (optional)
dim1,...,dim6 individual dimension names of the variable in NetCDF file (optional)
start vector of values specifying starting indices for reading data from each dimension (optional)
count vector of values specifying how many values to read in each dimension (optional)
long_name NetCDF attribute, a long descriptive name of variable (optional)
standard_name NetCDF attribute specifying the CF convention standard name of the variable (optional)
grid_mapping name of the grid this variable is mapped on (optional)
units NetCDF attribute of the units of the variable (optional)
missing_value Value of missing data to be written to file (optional)
ncid File ID for a file that remains open for various NCIO calls (optional)
subroutine nc_open(filename,ncid,[writable])filename name of the NetCDF file from which to read attribute
ncid integer variable to identify a NetCDF file through multiple NCIO calls
writable Switch to determine whether file should be opened for writing (optional, default TRUE)
subroutine nc_close(ncid)ncid integer variable to identify a NetCDF file to be closed