NAME
netcdf - Unidata’s Network Common Data Form (netCDF) library interface
SYNOPSIS
include netcdf.inc
Most Systems:
f77 ... -lnetcdf -lhdf5_hl -lhdf5 -lz -lm
CRAY PVP Systems:
f90 -dp -i64 ... -lnetcdf
Complete documentation for the netCDF libraries can be found at the
netCDF website: http://www.unidata.ucar.edu/software/netcdf/.
LIBRARY VERSION
This document describes versions 3 and 4 of Unidata netCDF data-access
interface for the FORTRAN programming language.
character*80 nf_inq_libvers(void)
Returns a string identifying the version of the netCDF library,
and when it was built, like: "3.1a of Aug 22 1996 12:57:47 $".
The RCS ident(1) command will find a string like "$Id: @(#) netcdf
library version 3.1a of Sep 6 1996 15:56:26 $" in the library. The
SCCS what(1) command will find a string like "netcdf library version
3.1a of Aug 23 1996 16:07:40 $".
RETURN VALUES
All netCDF functions (except nf_inq_libvers() and nf_strerror()) return
an integer status.
If this returned status value is not equal to NF_NOERR (zero), it
indicates that an error occurred. The possible status values are
defined in netcdf.inc.
character*80 nf_strerror(integer status)
Returns a string textual translation of the status value, like
"Attribute or variable name contains illegal characters" or "No
such file or directory".
FILE OPERATIONS
integer function nf_create(character*(*) path, integer cmode, integer
ncid)
Creates a new netCDF dataset at path, returning a netCDF ID in
ncid. The argument cmode may include the bitwise-or of the
following flags: NF_NOCLOBBER to protect existing datasets
(default silently blows them away), NF_SHARE for synchronous
dataset updates for classic format files (default is to buffer
accesses),
When a netCDF dataset is created, is is opened NF_WRITE. The
new netCDF dataset is in define mode. NF_64BIT_OFFSET. to
create a file in the 64-bit offset format (as opposed to classic
format, the default). NF_TRUE to create a netCDF-4/HDF5 file,
and NF_CLASSIC_MODEL to guarantee that netCDF-4/HDF5 files
maintain compatibility with the netCDF classic data model.
integer function nf__create(character*(*) path, integer cmode, integer
initialsize, integer chunksize, integer ncid)
Like nf_create() but has additional performance tuning
parameters.
The argument initialsize sets the initial size of the file at
creation time.
See nf__open() below for an explanation of the chunksize
parameter.
integer function nf_open(character*(*) path, integer mode, integer
ncid)
(Corresponds to ncopn() in version 2)
Opens a existing netCDF dataset at path returning a netCDF ID in
ncid. The type of access is described by the mode parameter,
which may include the bitwise-or of the following flags:
NF_WRITE for read-write access (default read-only), NF_SHARE for
synchronous dataset updates (default is to buffer accesses), and
NF_LOCK (not yet implemented).
As of NetCDF version 4.1, and if TRUE support was enabled when
the NetCDF library was built, the path parameter may specify a
TRUE URL. In this case, the access mode is forced to be read-
only.
integer function nf__open(character*(*) path, integer mode, integer
chunksize, integer ncid)
Like nf_open() but has an additional performance tuning
parameter.
The argument referenced by chunksize controls a space versus
time tradeoff, memory allocated in the netcdf library versus
number of system calls. Because of internal requirements, the
value may not be set to exactly the value requested. The actual
value chosen is returned by reference. Using the value
NF_SIZEHINT_DEFAULT causes the library to choose a default. How
the system choses the default depends on the system. On many
systems, the "preferred I/O block size" is available from the
stat() system call, struct stat member st_blksize. If this is
available it is used. Lacking that, twice the system pagesize is
used. Lacking a call to discover the system pagesize, we just
set default chunksize to 8192.
The chunksize is a property of a given open netcdf descriptor
ncid, it is not a persistent property of the netcdf dataset.
As with nf__open(), the path parameter may specify a TRUE URL,
but the tuning parameters are ignored.
integer function nf_redef(integer ncid)
(Corresponds to ncredf() in version 2)
Puts an open netCDF dataset into define mode, so dimensions,
variables, and attributes can be added or renamed and attributes
can be deleted.
integer function nf_enddef(integer ncid)
(Corresponds to ncendf() in version 2)
Takes an open netCDF dataset out of define mode. The changes
made to the netCDF dataset while it was in define mode are
checked and committed to disk if no problems occurred. Some
data values may be written as well, see "VARIABLE PREFILLING"
below. After a successful call, variable data can be read or
written to the dataset.
integer function nf__enddef(integer ncid, integer h_minfree, integer
v_align, integer v_minfree, integer r_align)
Like nf_enddef() but has additional performance tuning
parameters.
Caution: this function exposes internals of the netcdf version 1
file format. It may not be available on future netcdf
implementations.
The current netcdf file format has three sections, the "header"
section, the data section for fixed size variables, and the data
section for variables which have an unlimited dimension (record
variables). The header begins at the beginning of the file. The
index (offset) of the beginning of the other two sections is
contained in the header. Typically, there is no space between
the sections. This causes copying overhead to accrue if one
wishes to change the size of the sections, as may happen when
changing names of things, text attribute values, adding
attributes or adding variables. Also, for buffered i/o, there
may be advantages to aligning sections in certain ways.
The minfree parameters allow one to control costs of future
calls to nf_redef(), nf_enddef() by requesting that minfree
bytes be available at the end of the section. The h_minfree
parameter sets the pad at the end of the "header" section. The
v_minfree parameter sets the pad at the end of the data section
for fixed size variables.
The align parameters allow one to set the alignment of the
beginning of the corresponding sections. The beginning of the
section is rounded up to an index which is a multiple of the
align parameter. The flag value NF_ALIGN_CHUNK tells the library
to use the chunksize (see above) as the align parameter. The
v_align parameter controls the alignment of the beginning of the
data section for fixed size variables. The r_align parameter
controls the alignment of the beginning of the data section for
variables which have an unlimited dimension (record variables).
The file format requires mod 4 alignment, so the align
parameters are silently rounded up to multiples of 4. The usual
call, nf_enddef(ncid) is equivalent to nf__enddef(ncid, 0, 4, 0,
4).
The file format does not contain a "record size" value, this is
calculated from the sizes of the record variables. This
unfortunate fact prevents us from providing minfree and
alignment control of the "records" in a netcdf file. If you add
a variable which has an unlimited dimension, the third section
will always be copied with the new variable added.
integer function nf_sync(integer ncid)
(Corresponds to ncsnc() in version 2)
Unless the NF_SHARE bit is set in nf_open() or nf_create(),
accesses to the underlying netCDF dataset are buffered by the
library. This function synchronizes the state of the underlying
dataset and the library. This is done automatically by
nf_close() and nf_enddef().
integer function nf_abort(integer ncid)
(Corresponds to ncabor() in version 2)
You don’t need to call this function. This function is called
automatically by nf_close() if the netCDF was in define mode and
something goes wrong with the commit. If the netCDF dataset
isn’t in define mode, then this function is equivalent to
nf_close(). If it is called after nf_redef(), but before
nf_enddef(), the new definitions are not committed and the
dataset is closed. If it is called after nf_create() but before
nf_enddef(), the dataset disappears.
integer function nf_close(integer ncid)
(Corresponds to ncclos() in version 2)
Closes an open netCDF dataset. If the dataset is in define
mode, nf_enddef() will be called before closing. After a
dataset is closed, its ID may be reassigned to another dataset.
integer function nf_inq(integer ncid, integer ndims, integer nvars,
integer natts, integer unlimdimid)
integer function nf_inq_ndims(integer ncid, integer ndims)
integer function nf_inq_nvars(integer ncid, integer nvars)
integer function nf_inq_natts(integer ncid, integer natts)
integer function nf_inq_unlimdim(integer ncid, integer unlimdimid)
integer function nf_inq_format(integer ncid, integer formatn)
Use these functions to find out what is in a netCDF dataset.
Upon successful return, ndims will contain the number of
dimensions defined for this netCDF dataset, nvars will contain
the number of variables, natts will contain the number of
attributes, and unlimdimid will contain the dimension ID of the
unlimited dimension if one exists, or 0 otherwise. formatn will
contain the version number of the dataset <format>, one of
NF_FORMAT_CLASSIC, NF_FORMAT_64BIT, NF_FORMAT_NETCDF4, or
NF_FORMAT_NETCDF4_CLASSIC.
integer function nf_def_dim(integer ncid, character*(*) name, integer
len, integer dimid)
(Corresponds to ncddef() in version 2)
Adds a new dimension to an open netCDF dataset, which must be in
define mode. name is the dimension name. dimid will contain
the dimension ID of the newly created dimension.
USER DEFINED TYPES
Users many define types for a netCDF-4/HDF5 file (unless the
NF_CLASSIC_MODEL was used when the file was creates). Users may define
compound types, variable length arrays, enumeration types, and opaque
types.
integer function nf_def_compound(integer ncid, integer size,
character*(*) name, integer typeidp)
Define a compound type.
integer function nf_insert_compound(integer ncid, integer ,
character*(*) name, integer offset, integer field_typeid)
Insert an element into a compound type. May not be done after
type has been used, or after the type has been written by an
enddef.
integer function nf_insert_array_compound(integer ncid, integer ,
character*(*) name, integer offset, integer field_typeid,
integer ndims, integer dim_sizes(1))
Insert an array into a compound type.
integer function nf_inq_type(integer ncid, integer , character*(*)
name, integer sizep)
Learn about a type.
integer function nf_inq_compound(integer ncid, integer , character*(*)
name, integer sizep, integer nfieldsp)
integer function nf_inq_compound_name(integer ncid, integer ,
character*(*) name)
integer function nf_inq_compound_size(integer ncid, integer , integer
sizep)
integer function nf_inq_compound_nfields(integer ncid, integer ,
integer nfieldsp)
integer function nf_inq_compound_fieldname(integer ncid, integer ,
integer fieldid, character*(*) name)
integer function nf_inq_compound_fieldindex(integer ncid, integer ,
character*(*) name, integer fieldidp)
integer function nf_inq_compound_fieldoffset(integer ncid, integer ,
integer fieldid, integer offsetp)
integer function nf_inq_compound_fieldtype(integer ncid, integer ,
integer fieldid, integer field_typeid)
integer function nf_inq_compound_fieldndims(integer ncid, integer ,
integer fieldid, integer ndims)
integer function nf_inq_compound_fielddim_sizes(integer ncid, integer ,
integer fieldid, integer dim_sizes(1))
Learn about a compound type.
integer function nf_def_vlen(integer ncid, character*(*) name, integer
base_typeid, integer xtypep)
Create a varaible length array type.
integer function nf_inq_vlen(integer ncid, integer , character*(*)
name, integer datum_sizep, integer base_nc_typep)
Learn about a varaible length array type.
integer function nf_free_vlen(nc_vlen_t *vl)
Free memory comsumed by reading data of a varaible length array
type.
integer function nf_put_vlen_element(integer ncid, integer , void *
vlen_element, integer len, void * data)
Write one VLEN.
integer function nf_get_vlen_element(integer ncid, integer , void *
vlen_element, integer len, void * data)
Read one VLEN.
integer function nf_free_string(integer len, char **data)
Free memory comsumed by reading data of a string type.
integer function nf_inq_user_type(integer ncid, integer , character*(*)
name, integer , integer , integer , integer )
Learn about a user define type.
integer function nf_def_enum(integer ncid, integer base_typeid,
character*(*) name, integer typeidp)
Define an enumeration type.
integer function nf_insert_enum(integer ncid, integer base_typeid,
character*(*) name, const void *value)
Insert a name-value pair into enumeration type.
integer function nf_inq_enum_member(integer ncid, integer xtype,
integer idx, character*(*) name, void *value)
integer function nf_inq_enum_ident(integer ncid, integer xtype, integer
idx, integer*8 value, character*(*) identifier)
Learn about a name-value pair into enumeration type.
integer function nf_def_opaque(integer ncid, integer size,
character*(*) name, integer xtypep)
Create an opaque type.
integer function nf_inq_opaque(integer ncid, integer xtype,
character*(*) name, integer sizep)
Learn about opaque type.
GROUPS
Users may organize data into hierarchical groups in netCDF-4/HDF5 files
(unless NF_CLASSIC_MODEL was used when creating the file).
integer function nf_inq_grps(integer ncid, integer numgrps, integer
ncids(1))
Learn how many groups (and their ncids) are available from the
group represented by ncid.
integer function nf_inq_grpname(integer ncid, character*(*) name)
integer function nf_inq_grpname_full(integer ncid, integer len,
character*(*) name)
integer function nf_inq_grpname_len(integer ncid, integer len)
integer function nf_inq_grp_parent(integer ncid, integer ncid)
integer function nf_inq_grp_ncid(integer ncid, character*(*) name,
integer ncid)
integer function nf_inq_full_ncid(integer ncid, character*(*) name,
integer ncid)
Learn about a group.
integer function nf_inq_varids(integer ncid, integer nvars, integer )
Get the varids in a group.
integer function nf_inq_dimids(integer ncid, integer ndims, integer
dimids, integer include_parents)
Get the dimids in a group and (potentially) its parents.
integer function nf_inq_typeids(integer ncid, integer ntypes, integer
typeids(1))
Get the typeids of user-defined types in a group.
integer function nf_def_grp(integer ncid, character*(*) name, integer
ncid)
Create a group.
DIMENSIONS
integer function nf_inq_dimid(integer ncid, character*(*) name, integer
dimid)
(Corresponds to ncdid() in version 2)
Given a dimension name, returns the ID of a netCDF dimension in
dimid.
integer function nf_inq_dim(integer ncid, integer dimid, character*(*)
name, integer len)
integer function nf_inq_dimname(integer ncid, integer dimid,
character*(*) name)
integer function nf_inq_dimlen(integer ncid, integer dimid, integer
len)
Use these functions to find out about a dimension.
name should be big enough (NF_MAX_NAME) to hold the dimension
name as the name will be copied into your storage. The length
return parameter, len will contain the size of the dimension.
For the unlimited dimension, the returned length is the current
maximum value used for writing into any of the variables which
use the dimension.
integer function nf_rename_dim(integer ncid, integer dimid,
character*(*) name)
(Corresponds to ncdren() in version 2)
Renames an existing dimension in an open netCDF dataset. If the
new name is longer than the old name, the netCDF dataset must be
in define mode. You cannot rename a dimension to have the same
name as another dimension.
VARIABLES
integer function nf_def_var(integer ncid, character*(*) name, integer
xtype, integer ndims, integer dimids(1), integer varid)
(Corresponds to ncvdef() in version 2)
Adds a new variable to a netCDF dataset. The netCDF must be in
define mode. varid will be set to the netCDF variable ID.
integer function nf_inq_varid(integer ncid, character*(*) name, integer
varid)
(Corresponds to ncvid() in version 2)
Returns the ID of a netCDF variable in varid given its name.
integer function nf_inq_var(integer ncid, integer varid, character*(*)
name, integer xtype, integer ndims, integer dimids(1), integer
natts)
integer function nf_inq_varname(integer ncid, integer varid,
character*(*) name)
integer function nf_inq_vartype(integer ncid, integer varid, integer
xtype)
integer function nf_inq_varndims(integer ncid, integer varid, integer
ndims)
integer function nf_inq_vardimid(integer ncid, integer varid, integer
dimids(1))
integer function nf_inq_varnatts(integer ncid, integer varid, integer
natts)
Returns information about a netCDF variable, given its ID.
integer function nf_rename_var(integer ncid, integer varid,
character*(*) name)
(Corresponds to ncvren() in version 2)
Changes the name of a netCDF variable. If the new name is
longer than the old name, the netCDF must be in define mode.
You cannot rename a variable to have the name of any existing
variable.
VARIABLES in NETCDF-4 FILES
The following functions may only be used on variables in a
netCDF-4/HDF5 data file. These functions must be called after the
variable is defined, but before an enddef call.
integer function nf_def_var_deflate(integer ncid, integer varid,
integer shuffle, integer deflate, integer deflate_level)
Turn on compression and/or shuffle filter. (Shuffle filter is only
useful for integer data.)
integer function nf_inq_var_deflate(integer ncid, integer varid,
integer shufflep, integer deflatep, integer deflate_levelp)
Learn about a variable’s deflate settings.
integer function nf_def_var_fletcher32(integer ncid, integer varid,
integer fletcher32)
Turn on checksumming for a variable.
integer function nf_inq_var_fletcher32(integer ncid, integer varid,
integer fletcher32)
Learn about checksumming for a variable.
integer function nf_def_var_chunking(integer ncid, integer varid,
integer storage, integer chunksizesp(1))
Set chunksizes for a variable.
integer function nf_inq_var_chunking(integer ncid, integer varid,
integer storagep, integer chunksizesp(1))
Learn about chunksizes for a variable.
integer function nf_def_var_fill(integer ncid, integer varid, integer
no_fill, integer chunksizesp(1))
Set a fill value for a variable.
integer function nf_inq_var_fill(integer ncid, integer varid, integer
storagep, integer chunksizesp(1))
Learn the fill value for a variable.
integer function nf_def_var_endian(integer ncid, integer varid, integer
endian)
Set endianness of variable.
integer function nf_inq_var_endian(integer ncid, integer varid, integer
endianp)
Learn the endianness of a variable.
WRITING AND READING WHOLE VARIABLES
integer function nf_put_var_text(integer ncid, integer varid,
character*(*) out)
integer function nf_put_var_int1(integer ncid, integer varid, integer*1
out(1))
integer function nf_put_var_int2(integer ncid, integer varid, integer*2
out(1))
integer function nf_put_var_int(integer ncid, integer varid, integer
out(1))
integer function nf_put_var_real(integer ncid, integer varid, real
out(1))
integer function nf_put_var_double(integer ncid, integer varid,
doubleprecision out(1))
integer function nf_put_var_ubyte(integer ncid, integer varid,
integer*1 out(1))
integer function nf_put_var_ushort(integer ncid, integer varid,
integer*2 out(1))
integer function nf_put_var_uint(integer ncid, integer varid, integer*4
out(1))
integer function nf_put_var_(integer ncid, integer varid, integer*8
out(1))
integer function nf_put_var_uint64(integer ncid, integer varid,
integer*8 out(1))
integer function nf_put_var_string(integer ncid, integer varid,
character* out(1))
Writes an entire netCDF variable (i.e. all the values). The
netCDF dataset must be open and in data mode. The type of the
data is specified in the function name, and it is converted to
the external type of the specified variable, if possible,
otherwise an NF_ERANGE error is returned. Note that rounding is
not performed during the conversion. Floating point numbers are
truncated when converted to integers.
integer function nf_get_var_text(integer ncid, integer varid,
character*(*) in)
integer function nf_get_var_int1(integer ncid, integer varid, integer*1
in(1))
integer function nf_get_var_int2(integer ncid, integer varid, integer*2
in(1))
integer function nf_get_var_int(integer ncid, integer varid, integer
in(1))
integer function nf_get_var_real(integer ncid, integer varid, real
in(1))
integer function nf_get_var_double(integer ncid, integer varid,
doubleprecision in(1))
integer function nf_get_var_ubyte(integer ncid, integer varid,
integer*1 in(1))
integer function nf_get_var_ushort(integer ncid, integer varid,
integer*2 in(1))
integer function nf_get_var_uint(integer ncid, integer varid, integer*4
in(1))
integer function nf_get_var_(integer ncid, integer varid, integer*8
in(1))
integer function nf_get_var_uint64(integer ncid, integer varid,
integer*8 in(1))
integer function nf_get_var_string(integer ncid, integer varid,
character* in(1))
Reads an entire netCDF variable (i.e. all the values). The
netCDF dataset must be open and in data mode. The data is
converted from the external type of the specified variable, if
necessary, to the type specified in the function name. If
conversion is not possible, an NF_ERANGE error is returned.
WRITING AND READING ONE DATUM
integer function nf_put_var1_text(integer ncid, integer varid, integer
index(1), character*1 *out)
integer function nf_put_var1_int1(integer ncid, integer varid, integer
index(1), integer*1 *out)
integer function nf_put_var1_int2(integer ncid, integer varid, integer
index(1), integer*2 *out)
integer function nf_put_var1_int(integer ncid, integer varid, integer
index(1), integer *out)
integer function nf_put_var1_real(integer ncid, integer varid, integer
index(1), real *out)
integer function nf_put_var1_double(integer ncid, integer varid,
integer index(1), doubleprecision *out)
integer function nf_put_var1_ubyte(integer ncid, integer varid, integer
index(1), integer*1 *out)
integer function nf_put_var1_ushort(integer ncid, integer varid,
integer index(1), integer*2 *out)
integer function nf_put_var1_uint(integer ncid, integer varid, integer
index(1), integer*4 *out)
integer function nf_put_var1_(integer ncid, integer varid, integer
index(1), integer*8 *out)
integer function nf_put_var1_uint64(integer ncid, integer varid,
integer index(1), integer*8 *out)
integer function nf_put_var1_string(integer ncid, integer varid,
integer index(1), character* *out)
Puts a single data value into a variable at the position index
of an open netCDF dataset that is in data mode. The type of the
data is specified in the function name, and it is converted to
the external type of the specified variable, if possible,
otherwise an NF_ERANGE error is returned.
integer function nf_get_var1_text(integer ncid, integer varid, integer
index(1), character*1 in)
integer function nf_get_var1_int1(integer ncid, integer varid, integer
index(1), integer*1 in)
integer function nf_get_var1_int2(integer ncid, integer varid, integer
index(1), integer*2 in)
integer function nf_get_var1_int(integer ncid, integer varid, integer
index(1), integer in)
integer function nf_get_var1_real(integer ncid, integer varid, integer
index(1), real in)
integer function nf_get_var1_double(integer ncid, integer varid,
integer index(1), doubleprecision in)
integer function nf_get_var1_ubyte(integer ncid, integer varid, integer
index(1), integer*1 in)
integer function nf_get_var1_ushort(integer ncid, integer varid,
integer index(1), integer*2 in)
integer function nf_get_var1_uint(integer ncid, integer varid, integer
index(1), integer*4 in)
integer function nf_get_var1_(integer ncid, integer varid, integer
index(1), integer*8 in)
integer function nf_get_var1_uint64(integer ncid, integer varid,
integer index(1), integer*8 in)
integer function nf_get_var1_string(integer ncid, integer varid,
integer index(1), character* in)
Gets a single data value from a variable at the position index
of an open netCDF dataset that is in data mode. The data is
converted from the external type of the specified variable, if
necessary, to the type specified in the function name. If
conversion is not possible, an NF_ERANGE error is returned.
WRITING AND READING AN ARRAY
integer function nf_put_vara_text(integer ncid, integer varid, integer
start(1), integer count(1), character*(*) out)
integer function nf_put_vara_int1(integer ncid, integer varid, integer
start(1), integer count(1), integer*1 out(1))
integer function nf_put_vara_int2(integer ncid, integer varid, integer
start(1), integer count(1), integer*2 out(1))
integer function nf_put_vara_int(integer ncid, integer varid, integer
start(1), integer count(1), integer out(1))
integer function nf_put_vara_real(integer ncid, integer varid, integer
start(1), integer count(1), real out(1))
integer function nf_put_vara_double(integer ncid, integer varid,
integer start(1), integer count(1), doubleprecision out(1))
integer function nf_put_vara_ubyte(integer ncid, integer varid, integer
start(1), integer count(1), integer*1 out(1))
integer function nf_put_vara_ushort(integer ncid, integer varid,
integer start(1), integer count(1), integer*2 out(1))
integer function nf_put_vara_uint(integer ncid, integer varid, integer
start(1), integer count(1), integer*4 out(1))
integer function nf_put_vara_(integer ncid, integer varid, integer
start(1), integer count(1), integer*8 out(1))
integer function nf_put_vara_uint64(integer ncid, integer varid,
integer start(1), integer count(1), integer*8 out(1))
integer function nf_put_vara_string(integer ncid, integer varid,
integer start(1), integer count(1), character* out(1))
Writes an array section of values into a netCDF variable of an
open netCDF dataset, which must be in data mode. The array
section is specified by the start and count vectors, which give
the starting index and count of values along each dimension of
the specified variable. The type of the data is specified in
the function name and is converted to the external type of the
specified variable, if possible, otherwise an NF_ERANGE error is
returned.
integer function nf_get_vara_text(integer ncid, integer varid, integer
start(1), integer count(1), character*(*) in)
integer function nf_get_vara_int1(integer ncid, integer varid, integer
start(1), integer count(1), integer*1 in(1))
integer function nf_get_vara_int2(integer ncid, integer varid, integer
start(1), integer count(1), integer*2 in(1))
integer function nf_get_vara_int(integer ncid, integer varid, integer
start(1), integer count(1), integer in(1))
integer function nf_get_vara_real(integer ncid, integer varid, integer
start(1), integer count(1), real in(1))
integer function nf_get_vara_double(integer ncid, integer varid,
integer start(1), integer count(1), doubleprecision in(1))
integer function nf_get_vara_ubyte(integer ncid, integer varid, integer
start(1), integer count(1), integer*1 in(1))
integer function nf_get_vara_ushort(integer ncid, integer varid,
integer start(1), integer count(1), integer*2 in(1))
integer function nf_get_vara_uint(integer ncid, integer varid, integer
start(1), integer count(1), integer*4 in(1))
integer function nf_get_vara_(integer ncid, integer varid, integer
start(1), integer count(1), integer*8 in(1))
integer function nf_get_vara_uint64(integer ncid, integer varid,
integer start(1), integer count(1), integer*8 in(1))
integer function nf_get_vara_string(integer ncid, integer varid,
integer start(1), integer count(1), character* in(1))
Reads an array section of values from a netCDF variable of an
open netCDF dataset, which must be in data mode. The array
section is specified by the start and count vectors, which give
the starting index and count of values along each dimension of
the specified variable. The data is converted from the external
type of the specified variable, if necessary, to the type
specified in the function name. If conversion is not possible,
an NF_ERANGE error is returned.
WRITING AND READING A SLICED ARRAY
integer function nf_put_vars_text(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), character*(*)
out)
integer function nf_put_vars_int1(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*1 out(1))
integer function nf_put_vars_int2(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*2 out(1))
integer function nf_put_vars_int(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer out(1))
integer function nf_put_vars_real(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), real out(1))
integer function nf_put_vars_double(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1),
doubleprecision out(1))
integer function nf_put_vars_ubyte(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*1 out(1))
integer function nf_put_vars_ushort(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), integer*2
out(1))
integer function nf_put_vars_uint(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*4 out(1))
integer function nf_put_vars_(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*8 out(1))
integer function nf_put_vars_uint64(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), integer*8
out(1))
integer function nf_put_vars_string(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1),
character* out(1))
These functions are used for strided output, which is like the
array section output described above, except that the sampling
stride (the interval between accessed values) is specified for
each dimension. For an explanation of the sampling stride
vector, see COMMON ARGUMENTS DESCRIPTIONS below.
integer function nf_get_vars_text(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), character*(*) in)
integer function nf_get_vars_int1(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*1 in(1))
integer function nf_get_vars_int2(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*2 in(1))
integer function nf_get_vars_int(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer in(1))
integer function nf_get_vars_real(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), real in(1))
integer function nf_get_vars_double(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1),
doubleprecision in(1))
integer function nf_get_vars_ubyte(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*1 in(1))
integer function nf_get_vars_ushort(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), integer*2
in(1))
integer function nf_get_vars_uint(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*4 in(1))
integer function nf_get_vars_(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), integer*8 in(1))
integer function nf_get_vars_uint64(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), integer*8
in(1))
integer function nf_get_vars_string(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1),
character* in(1))
These functions are used for strided input, which is like the
array section input described above, except that the sampling
stride (the interval between accessed values) is specified for
each dimension. For an explanation of the sampling stride
vector, see COMMON ARGUMENTS DESCRIPTIONS below.
WRITING AND READING A MAPPED ARRAY
integer function nf_put_varm_text(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap,
character*(*) out)
integer function nf_put_varm_int1(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*1
out(1))
integer function nf_put_varm_int2(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*2
out(1))
integer function nf_put_varm_int(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer
out(1))
integer function nf_put_varm_real(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, real
out(1))
integer function nf_put_varm_double(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
doubleprecision out(1))
integer function nf_put_varm_ubyte(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*1
out(1))
integer function nf_put_varm_ushort(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
integer*2 out(1))
integer function nf_put_varm_uint(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*4
out(1))
integer function nf_put_varm_(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*8
out(1))
integer function nf_put_varm_uint64(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
integer*8 out(1))
integer function nf_put_varm_string(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
character* out(1))
These functions are used for mapped output, which is like
strided output described above, except that an additional index
mapping vector is provided to specify the in-memory arrangement
of the data values. For an explanation of the index mapping
vector, see COMMON ARGUMENTS DESCRIPTIONS below.
integer function nf_get_varm_text(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap,
character*(*) in)
integer function nf_get_varm_int1(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*1
in(1))
integer function nf_get_varm_int2(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*2
in(1))
integer function nf_get_varm_int(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer
in(1))
integer function nf_get_varm_real(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, real in(1))
integer function nf_get_varm_double(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
doubleprecision in(1))
integer function nf_get_varm_ubyte(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*1
in(1))
integer function nf_get_varm_ushort(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
integer*2 in(1))
integer function nf_get_varm_uint(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*4
in(1))
integer function nf_get_varm_(integer ncid, integer varid, integer
start(1), integer count(1), integer stride(1), imap, integer*8
in(1))
integer function nf_get_varm_uint64(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
integer*8 in(1))
integer function nf_get_varm_string(integer ncid, integer varid,
integer start(1), integer count(1), integer stride(1), imap,
character* in(1))
These functions are used for mapped input, which is like strided
input described above, except that an additional index mapping
vector is provided to specify the in-memory arrangement of the
data values. For an explanation of the index mapping vector,
see COMMON ARGUMENTS DESCRIPTIONS below.
ATTRIBUTES
integer function nf_put_att_text(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, character*(*)
out)
integer function nf_put_att_int1(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, integer*1
out(1))
integer function nf_put_att_int2(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, integer*2
out(1))
integer function nf_put_att_int(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, integer out(1))
integer function nf_put_att_real(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, real out(1))
integer function nf_put_att_double(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, doubleprecision
out(1))
integer function nf_put_att_ubyte(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, integer*1
out(1))
integer function nf_put_att_ushort(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, integer*2
out(1))
integer function nf_put_att_uint(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, integer*4
out(1))
integer function nf_put_att_(integer ncid, integer varid, character*(*)
name, integer xtype, integer len, integer*8 out(1))
integer function nf_put_att_uint64(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, integer*8
out(1))
integer function nf_put_att_string(integer ncid, integer varid,
character*(*) name, integer xtype, integer len, character*
out(1))
integer function nf_put_att(integer ncid, integer varid, character*(*)
name, integer xtype, integer len, void * ip)
integer function nf_get_att(integer ncid, integer varid, character*(*)
name, void * ip)
Unlike variables, attributes do not have separate functions for
defining and writing values. This family of functions defines a
new attribute with a value or changes the value of an existing
attribute. If the attribute is new, or if the space required to
store the attribute value is greater than before, the netCDF
dataset must be in define mode. The parameter len is the number
of values from out to transfer. It is often one, except that
for nf_put_att_text() it will usually be len_trim(out).
For these functions, the type component of the function name
refers to the in-memory type of the value, whereas the xtype
argument refers to the external type for storing the value. An
NF_ERANGE error results if a conversion between these types is
not possible. In this case the value is represented with the
appropriate fill-value for the associated external type.
integer function nf_inq_attname(integer ncid, integer varid, integer
attnum, character*(*) name)
Gets the name of an attribute, given its variable ID and
attribute number. This function is useful in generic
applications that need to get the names of all the attributes
associated with a variable, since attributes are accessed by
name rather than number in all other attribute functions. The
number of an attribute is more volatile than the name, since it
can change when other attributes of the same variable are
deleted. The attributes for each variable are numbered from 1
(the first attribute) to nvatts, where nvatts is the number of
attributes for the variable, as returned from a call to
nf_inq_varnatts().
integer function nf_inq_att(integer ncid, integer varid, character*(*)
name, integer xtype, integer len)
integer function nf_inq_attid(integer ncid, integer varid,
character*(*) name, integer attnum)
integer function nf_inq_atttype(integer ncid, integer varid,
character*(*) name, integer xtype)
integer function nf_inq_attlen(integer ncid, integer varid,
character*(*) name, integer len)
These functions return information about a netCDF attribute,
given its variable ID and name. The information returned is the
external type in xtype and the number of elements in the
attribute as len.
integer function nf_copy_att(integer ncid, integer varid_in,
character*(*) name, integer ncid_out, integer varid_out)
Copies an attribute from one netCDF dataset to another. It can
also be used to copy an attribute from one variable to another
within the same netCDF. ncid_in is the netCDF ID of an input
netCDF dataset from which the attribute will be copied.
varid_in is the ID of the variable in the input netCDF dataset
from which the attribute will be copied, or NF_GLOBAL for a
global attribute. name is the name of the attribute in the
input netCDF dataset to be copied. ncid_out is the netCDF ID of
the output netCDF dataset to which the attribute will be copied.
It is permissible for the input and output netCDF ID’s to be the
same. The output netCDF dataset should be in define mode if the
attribute to be copied does not already exist for the target
variable, or if it would cause an existing target attribute to
grow. varid_out is the ID of the variable in the output netCDF
dataset to which the attribute will be copied, or NF_GLOBAL to
copy to a global attribute.
integer function nf_rename_att(integer ncid, integer varid,
character*(*) name, character*(*) newname)
Changes the name of an attribute. If the new name is longer
than the original name, the netCDF must be in define mode. You
cannot rename an attribute to have the same name as another
attribute of the same variable. name is the original attribute
name. newname is the new name to be assigned to the specified
attribute. If the new name is longer than the old name, the
netCDF dataset must be in define mode.
integer function nf_del_att(integer ncid, integer varid, character*(*)
name)
Deletes an attribute from a netCDF dataset. The dataset must be
in define mode.
integer function nf_get_att_text(integer ncid, integer varid,
character*(*) name, character*(*) in)
integer function nf_get_att_int1(integer ncid, integer varid,
character*(*) name, integer*1 in(1))
integer function nf_get_att_int2(integer ncid, integer varid,
character*(*) name, integer*2 in(1))
integer function nf_get_att_int(integer ncid, integer varid,
character*(*) name, integer in(1))
integer function nf_get_att_real(integer ncid, integer varid,
character*(*) name, real in(1))
integer function nf_get_att_double(integer ncid, integer varid,
character*(*) name, doubleprecision in(1))
integer function nf_get_att_ubyte(integer ncid, integer varid,
character*(*) name, integer*1 in(1))
integer function nf_get_att_ushort(integer ncid, integer varid,
character*(*) name, integer*2 in(1))
integer function nf_get_att_uint(integer ncid, integer varid,
character*(*) name, integer*4 in(1))
integer function nf_get_att_(integer ncid, integer varid, character*(*)
name, integer*8 in(1))
integer function nf_get_att_uint64(integer ncid, integer varid,
character*(*) name, integer*8 in(1))
integer function nf_get_att_string(integer ncid, integer varid,
character*(*) name, character* in(1))
Gets the value(s) of a netCDF attribute, given its variable ID
and name. Converts from the external type to the type specified
in the function name, if possible, otherwise returns an
NF_ERANGE error. All elements of the vector of attribute values
are returned, so you must allocate enough space to hold them.
If you don’t know how much space to reserve, call
nf_inq_attlen() first to find out the length of the attribute.
COMMON ARGUMENT DESCRIPTIONS
In this section we define some common arguments which are used in the
"FUNCTION DESCRIPTIONS" section.
integer ncid
is the netCDF ID returned from a previous, successful call to
nf_open() or nf_create()
character*(*) name
is the name of a dimension, variable, or attribute. The names of
dimensions, variables and attributes consist of arbitrary
sequences of alphanumeric characters (as well as underscore ’_’,
period ’.’ and hyphen ’-’), beginning with a letter or
underscore. (However names commencing with underscore are
reserved for system use.) Case is significant in netCDF names. A
zero-length name is not allowed.
The maximum allowable number of characters
is NF_MAX_NAME.
integer xtype
specifies the external data type of a netCDF variable or
attribute and is one of the following: NF_BYTE, NF_CHAR,
NF_SHORT, NF_INT, NF_FLOAT, or NF_DOUBLE. These are used to
specify 8-bit integers, characters, 16-bit integers, 32-bit
integers, 32-bit IEEE floating point numbers, and 64-bit IEEE
floating-point numbers, respectively.
integer dimids(1)
is a vector of dimension ID’s and defines the shape of a netCDF
variable. The size of the vector shall be greater than or equal
to the rank (i.e. the number of dimensions) of the variable
(ndims). The vector shall be ordered by the speed with which a
dimension varies: dimids(1) shall be the dimension ID of the
most rapidly varying dimension and dimids(ndims) shall be the
dimension ID of the most slowly varying dimension. The maximum
possible number of dimensions for a variable is given by the
symbolic constant NF_MAX_VAR_DIMS.
integer dimid
is the ID of a netCDF dimension. netCDF dimension ID’s are
allocated sequentially from the positive integers beginning with
1.
integer ndims
is either the total number of dimensions in a netCDF dataset or
the rank (i.e. the number of dimensions) of a netCDF variable.
The value shall not be negative or greater than the symbolic
constant NF_MAX_VAR_DIMS.
integer varid
is the ID of a netCDF variable or (for the attribute-access
functions) the symbolic constant NF_GLOBAL, which is used to
reference global attributes. netCDF variable ID’s are allocated
sequentially from the positive integers beginning with 1.
integer natts
is the number of global attributes in a netCDF dataset for the
nf_inquire() function or the number of attributes associated
with a netCDF variable for the nf_varinq() function.
integer index(1)
specifies the indicial coordinates of the netCDF data value to
be accessed. The indices start at 1; thus, for example, the
first data value of a two-dimensional variable is (1,1). The
size of the vector shall be at least the rank of the associated
netCDF variable and its elements shall correspond, in order, to
the variable’s dimensions.
integer start(1)
specifies the starting point for accessing a netCDF variable’s
data values in terms of the indicial coordinates of the corner
of the array section. The indices start at 1; thus, the first
data value of a variable is (1, 1, ..., 1). The size of the
vector shall be at least the rank of the associated netCDF
variable and its elements shall correspond, in order, to the
variable’s dimensions.
integer count(1)
specifies the number of indices selected along each dimension of
the array section. Thus, to access a single value, for example,
specify count as (1, 1, ..., 1). Note that, for strided I/O,
this argument must be adjusted to be compatible with the stride
and start arguments so that the interaction of the three does
not attempt to access an invalid data co-ordinate. The elements
of the count vector correspond, in order, to the variable’s
dimensions.
integer stride(1)
specifies the sampling interval along each dimension of the
netCDF variable. The elements of the stride vector correspond,
in order, to the netCDF variable’s dimensions (stride(1)) gives
the sampling interval along the most rapidly varying dimension
of the netCDF variable). Sampling intervals are specified in
type-independent units of elements (a value of 1 selects
consecutive elements of the netCDF variable along the
corresponding dimension, a value of 2 selects every other
element, etc.).
imap specifies the mapping between the dimensions of a netCDF
variable and the in-memory structure of the internal data array.
The elements of the index mapping vector correspond, in order,
to the netCDF variable’s dimensions (imap(1) gives the distance
between elements of the internal array corresponding to the most
rapidly varying dimension of the netCDF variable). Distances
between elements are specified in type-independent units of
elements (the distance between internal elements that occupy
adjacent memory locations is 1 and not the element’s byte-length
as in netCDF 2).
VARIABLE PREFILLING
By default, the netCDF interface sets the values of all newly-defined
variables of finite length (i.e. those that do not have an unlimited,
dimension) to the type-dependent fill-value associated with each
variable. This is done when nf_enddef() is called. The fill-value for
a variable may be changed from the default value by defining the
attribute ‘_FillValue’ for the variable. This attribute must have the
same type as the variable and be of length one.
Variables with an unlimited dimension are also prefilled, but on an ‘as
needed’ basis. For example, if the first write of such a variable is
to position 5, then positions 1 through 4 (and no others) would be set
to the fill-value at the same time.
This default prefilling of data values may be disabled by or’ing the
NF_NOFILL flag into the mode parameter of nf_open() or nf_create(), or,
by calling the function nf_set_fill() with the argument NF_NOFILL. For
variables that do not use the unlimited dimension, this call must be
made before nf_enddef(). For variables that use the unlimited
dimension, this call may be made at any time.
One can obtain increased performance of the netCDF interface by using
this feature, but only at the expense of requiring the application to
set every single data value. The performance enhancing behavior of
this function is dependent on the particulars of the implementation and
dataset format. The flag value controlled by nf_set_fill() is per
netCDF ID, not per variable or per write. Allowing this to change
affects the degree to which a program can be effectively parallelized.
Given all of this, we state that the use of this feature may not be
available (or even needed) in future releases. Programmers are
cautioned against heavy reliance upon this feature.
integer function nf_setfill(integer ncid, integer fillmode, integer
old_fillemode)
Determines whether or not variable prefilling will be done (see
above). The netCDF dataset shall be writable. fillmode is
either NF_FILL to enable prefilling (the default) or NF_NOFILL
to disable prefilling. This function returns the previous
setting in old_fillmode.
MPP FUNCTION DESCRIPTIONS
Additional functions for use on SGI/Cray MPP machines (_CRAYMPP).
These are used to set and inquire which PE is the base for MPP for a
particular netCDF. These are only relevant when using the SGI/Cray
‘‘global’’ Flexible File I/O layer and desire to have only a subset of
PEs to open the specific netCDF file. For technical reasons, these
functions are available on all platforms. On a platform other than
SGI/Cray MPP, it is as if only processor available were processor 0.
To use this feature, you need to specify a communicator group and call
glio_group_mpi() or glio_group_shmem() prior to the netCDF nf_open()
and nf_create() calls.
integer function nf__create_mp(character*(*) path, integer cmode,
integer initialsize, integer pe, integer chunksize, integer
ncid)
Like nf__create() but allows the base PE to be set.
The argument pe sets the base PE at creation time. In the MPP
environment, nf__create() and nf_create() set the base PE to
processor zero by default.
integer function nf__open_mp(character*(*) path, integer mode, integer
pe, integer chunksize, integer ncid)
Like nf__open() but allows the base PE to be set. The argument
pe sets the base PE at creation time. In the MPP environment,
nf__open() and nf_open() set the base PE to processor zero by
default.
integer function nf_inq_base_pe(integer ncid, integer pe)
Inquires of the netCDF dataset which PE is being used as the
base for MPP use. This is safe to use at any time.
integer function nf_set_base_pe(integer ncid, integer pe)
Resets the base PE for the netCDF dataset. Only perform this
operation when the affected communicator group synchronizes
before and after the call. This operation is very risky and
should only be contemplated under only the most extreme cases.
ENVIRONMENT VARIABLES
NETCDF_FFIOSPEC
Specifies the Flexible File I/O buffers for netCDF I/O when
executing under the UNICOS operating system (the variable is
ignored on other operating systems). An appropriate specification
can greatly increase the efficiency of netCDF I/O -- to the extent
that it can actually surpass FORTRAN binary I/O. This environment
variable has been made a little more generalized, such that other
FFIO option specifications can now be added. The default
specification is bufa:336:2, unless a current FFIO specification is
in operation, which will be honored. See UNICOS Flexible File I/O
for more information.
MAILING-LISTS
Both a mailing list and a digest are available for discussion of the
netCDF interface and announcements about netCDF bugs, fixes, and
enhancements. To begin or change your subscription to either the
mailing-list or the digest, send one of the following in the body (not
the subject line) of an email message to "majordomo@unidata.ucar.edu".
Use your email address in place of jdoe@host.inst.domain.
To subscribe to the netCDF mailing list:
subscribe netcdfgroup jdoe@host.inst.domain
To unsubscribe from the netCDF mailing list:
unsubscribe netcdfgroup jdoe@host.inst.domain
To subscribe to the netCDF digest:
subscribe netcdfdigest jdoe@host.inst.domain
To unsubscribe from the netCDF digest:
unsubscribe netcdfdigest jdoe@host.inst.domain
To retrieve the general introductory information for the mailing list:
info netcdfgroup
To get a synopsis of other majordomo commands:
help
SEE ALSO
ncdump(1), ncgen(1), netcdf(3f).
netCDF Users Guide, published by the Unidata Program Center,
University Corporation for Atmospheric Research, located in Boulder,
Colorado.
NetCDF home page at http:/www.unidata.ucar.edu/netcdf.