1NETCDF(3) UNIDATA LIBRARY FUNCTIONS NETCDF(3)
2
6 netcdf - Unidata's Network Common Data Form (netCDF) library interface
7
9 #include "netcdf.h"
10 cc ... -lnetcdf -lhdf5_hl -lhdf5 -lz -lm
13 Complete documentation for the netCDF libraries can be found at the
15 netCDF website: http://www.unidata.ucar.edu/software/netcdf/.
16
19 This document describes versions 3 and 4 of Unidata netCDF data-access
20 interface for the C programming language.
21 const char* nc_inq_libvers()
23 Returns a string identifying the version of the netCDF library,
25 and when it was built, like: "3.1a of Aug 22 1996 12:57:47 $".
26 The RCS ident(1) command will find a string like "$Id: @(#) netcdf li‐
28 brary version 3.1a of Sep 6 1996 15:56:26 $" in the library. The SCCS
29 what(1) command will find a string like "netcdf library version 3.1a of
30 Aug 23 1996 16:07:40 $".
31
33 All netCDF functions (except nc_inq_libvers() and nc_strerror()) return
34 an integer status.
35 If this returned status value is not equal to NC_NOERR (zero), it indi‐
37 cates that an error occurred. The possible status values are defined in
38 system include file <errno.h> and in "netcdf.h".
39 const char* nc_strerror(int status)
41 Returns a string textual translation of the status value, like
43 "Attribute or variable name contains illegal characters" or "No
44 such file or directory".
45
48 int nc_create(const char path[], int cmode, int* ncid)
49 Creates a new netCDF dataset at path, returning a netCDF ID in
51 ncid. The argument cmode may include the bitwise-or of the fol‐
52 lowing flags: NC_NOCLOBBER to protect existing datasets (default
53 silently blows them away), NC_SHARE for synchronous dataset up‐
54 dates for classic format files (default is to buffer accesses),
55 When a netCDF dataset is created, is is opened NC_WRITE. The
57 new netCDF dataset is in define mode. NC_64BIT_OFFSET. to cre‐
58 ate a file in the 64-bit offset format (as opposed to classic
59 format, the default). NC_TRUE to create a netCDF-4/HDF5 file,
60 and NC_CLASSIC_MODEL to guarantee that netCDF-4/HDF5 files main‐
61 tain compatibility with the netCDF classic data model.
62 int nc__create(const char path[], int cmode, size_t initialsize,
64 size_t* chunksize, int* ncid)
65 Like nc_create() but has additional performance tuning parame‐
67 ters.
68 The argument initialsize sets the initial size of the file at
70 creation time.
71 See nc__open() below for an explanation of the chunksize parame‐
73 ter.
74 int nc_open(const char path[], int mode, int* ncid)
76 (Corresponds to ncopen() in version 2)
78 Opens a existing netCDF dataset at path returning a netCDF ID in
80 ncid. The type of access is described by the mode parameter,
81 which may include the bitwise-or of the following flags:
82 NC_WRITE for read-write access (default read-only), NC_SHARE for
83 synchronous dataset updates (default is to buffer accesses), and
84 NC_LOCK (not yet implemented).
85 As of NetCDF version 4.1, and if TRUE support was enabled when
87 the NetCDF library was built, the path parameter may specify a
88 TRUE URL. In this case, the access mode is forced to be read-on‐
89 ly.
90 int nc__open(const char path[], int mode, size_t* chunksize, int* ncid)
92 Like nc_open() but has an additional performance tuning parame‐
94 ter.
95 The argument referenced by chunksize controls a space versus
97 time tradeoff, memory allocated in the netcdf library versus
98 number of system calls. Because of internal requirements, the
99 value may not be set to exactly the value requested. The actual
100 value chosen is returned by reference. Using the value NC_SIZE‐
101 HINT_DEFAULT causes the library to choose a default. How the
102 system choses the default depends on the system. On many sys‐
103 tems, the "preferred I/O block size" is available from the
104 stat() system call, struct stat member st_blksize. If this is
105 available it is used. Lacking that, twice the system pagesize is
106 used. Lacking a call to discover the system pagesize, we just
107 set default chunksize to 8192.
108 The chunksize is a property of a given open netcdf descriptor
110 ncid, it is not a persistent property of the netcdf dataset.
111 As with nc__open(), the path parameter may specify a TRUE URL,
113 but the tuning parameters are ignored.
114 int nc_redef(int ncid)
116 (Corresponds to ncredef() in version 2)
118 Puts an open netCDF dataset into define mode, so dimensions,
120 variables, and attributes can be added or renamed and attributes
121 can be deleted.
122 int nc_enddef(int ncid)
124 (Corresponds to ncendef() in version 2)
126 Takes an open netCDF dataset out of define mode. The changes
128 made to the netCDF dataset while it was in define mode are
129 checked and committed to disk if no problems occurred. Some da‐
130 ta values may be written as well, see "VARIABLE PREFILLING" be‐
131 low. After a successful call, variable data can be read or
132 written to the dataset.
133 int nc__enddef(int ncid, size_t h_minfree, size_t v_align, size_t
135 v_minfree, size_t r_align)
136 Like nc_enddef() but has additional performance tuning parame‐
138 ters.
139 Caution: this function exposes internals of the netcdf version 1
141 file format. It may not be available on future netcdf implemen‐
142 tations.
143 The current netcdf file format has three sections, the "header"
145 section, the data section for fixed size variables, and the data
146 section for variables which have an unlimited dimension (record
147 variables). The header begins at the beginning of the file. The
148 index (offset) of the beginning of the other two sections is
149 contained in the header. Typically, there is no space between
150 the sections. This causes copying overhead to accrue if one
151 wishes to change the size of the sections, as may happen when
152 changing names of things, text attribute values, adding at‐
153 tributes or adding variables. Also, for buffered i/o, there may
154 be advantages to aligning sections in certain ways.
155 The minfree parameters allow one to control costs of future
157 calls to nc_redef(), nc_enddef() by requesting that minfree
158 bytes be available at the end of the section. The h_minfree pa‐
159 rameter sets the pad at the end of the "header" section. The
160 v_minfree parameter sets the pad at the end of the data section
161 for fixed size variables.
162 The align parameters allow one to set the alignment of the be‐
164 ginning of the corresponding sections. The beginning of the sec‐
165 tion is rounded up to an index which is a multiple of the align
166 parameter. The flag value NC_ALIGN_CHUNK tells the library to
167 use the chunksize (see above) as the align parameter. The
168 v_align parameter controls the alignment of the beginning of the
169 data section for fixed size variables. The r_align parameter
170 controls the alignment of the beginning of the data section for
171 variables which have an unlimited dimension (record variables).
172 The file format requires mod 4 alignment, so the align parame‐
174 ters are silently rounded up to multiples of 4. The usual call,
175 nc_enddef(ncid) is equivalent to nc__enddef(ncid, 0, 4, 0, 4).
176 The file format does not contain a "record size" value, this is
178 calculated from the sizes of the record variables. This unfortu‐
179 nate fact prevents us from providing minfree and alignment con‐
180 trol of the "records" in a netcdf file. If you add a variable
181 which has an unlimited dimension, the third section will always
182 be copied with the new variable added.
183 int nc_sync(int ncid)
185 (Corresponds to ncsync() in version 2)
187 Unless the NC_SHARE bit is set in nc_open() or nc_create(), ac‐
189 cesses to the underlying netCDF dataset are buffered by the li‐
190 brary. This function synchronizes the state of the underlying
191 dataset and the library. This is done automatically by
192 nc_close() and nc_enddef().
193 int nc_abort(int ncid)
195 (Corresponds to ncabort() in version 2)
197 You don't need to call this function. This function is called
199 automatically by nc_close() if the netCDF was in define mode and
200 something goes wrong with the commit. If the netCDF dataset
201 isn't in define mode, then this function is equivalent to
202 nc_close(). If it is called after nc_redef(), but before
203 nc_enddef(), the new definitions are not committed and the
204 dataset is closed. If it is called after nc_create() but before
205 nc_enddef(), the dataset disappears.
206 int nc_close(int ncid)
208 (Corresponds to ncclose() in version 2)
210 Closes an open netCDF dataset. If the dataset is in define
212 mode, nc_enddef() will be called before closing. After a
213 dataset is closed, its ID may be reassigned to another dataset.
214 int nc_inq(int ncid, int* ndims, int* nvars, int* natts, int* un‐
216 limdimid)
217 int nc_inq_ndims(int ncid, int* ndims)
219 int nc_inq_nvars(int ncid, int* nvars)
221 int nc_inq_natts(int ncid, int* natts)
223 int nc_inq_unlimdim(int ncid, int* unlimdimid)
225 int nc_inq_format(int ncid, int* formatn)
227 Use these functions to find out what is in a netCDF dataset.
229 Upon successful return, ndims will contain the number of dimen‐
230 sions defined for this netCDF dataset, nvars will contain the
231 number of variables, natts will contain the number of at‐
232 tributes, and unlimdimid will contain the dimension ID of the
233 unlimited dimension if one exists, or -1 otherwise. formatn
234 will contain the version number of the dataset <format>, one of
235 NC_FORMAT_CLASSIC, NC_FORMAT_64BIT, NC_FORMAT_NETCDF4, or
236 NC_FORMAT_NETCDF4_CLASSIC. If any of the return parameters is a
237 NULL pointer, then the corresponding information will not be re‐
238 turned; hence, no space need be allocated for it.
239 int nc_def_dim(int ncid, const char name[], size_t len, int* dimid)
241 (Corresponds to ncdimdef() in version 2)
243 Adds a new dimension to an open netCDF dataset, which must be in
245 define mode. name is the dimension name. If dimid is not a
246 NULL pointer then upon successful completion dimid will contain
247 the dimension ID of the newly created dimension.
248
251 Users many define types for a netCDF-4/HDF5 file (unless the NC_CLAS‐
252 SIC_MODEL was used when the file was creates). Users may define com‐
253 pound types, variable length arrays, enumeration types, and opaque
254 types.
255 int nc_def_compound(int ncid, size_t size, const char name[], int*
259 typeidp)
260 Define a compound type.
262 int nc_insert_compound(int ncid, nc_type , const char name[], size_t
264 offset, nc_type field_typeid)
265 Insert an element into a compound type. May not be done after
267 type has been used, or after the type has been written by an
268 enddef.
269 int nc_insert_array_compound(int ncid, nc_type , const char name[],
271 size_t offset, nc_type field_typeid, int ndims, const int
272 dim_sizes[])
273 Insert an array into a compound type.
275 int nc_inq_type(int ncid, nc_type , char name[], size_t* sizep)
277 Learn about a type.
279 int nc_inq_compound(int ncid, nc_type , char name[], size_t* sizep,
281 size_t* nfieldsp)
282 int nc_inq_compound_name(int ncid, nc_type , char name[])
284 int nc_inq_compound_size(int ncid, nc_type , size_t* sizep)
286 int nc_inq_compound_nfields(int ncid, nc_type , size_t* nfieldsp)
288 int nc_inq_compound_fieldname(int ncid, nc_type , int fieldid, char
290 name[])
291 int nc_inq_compound_fieldindex(int ncid, nc_type , const char name[],
293 int* fieldidp)
294 int nc_inq_compound_fieldoffset(int ncid, nc_type , int fieldid,
296 size_t* offsetp)
297 int nc_inq_compound_fieldtype(int ncid, nc_type , int fieldid, nc_type*
299 field_typeid)
300 int nc_inq_compound_fieldndims(int ncid, nc_type , int fieldid, int*
302 ndims)
303 int nc_inq_compound_fielddim_sizes(int ncid, nc_type , int fieldid, int
305 dim_sizes[])
306 Learn about a compound type.
308 int nc_def_vlen(int ncid, const char name[], nc_type base_typeid,
310 nc_type* xtypep)
311 Create a varaible length array type.
313 int nc_inq_vlen(int ncid, nc_type , char name[], size_t* datum_sizep,
315 nc_type* base_nc_typep)
316 Learn about a varaible length array type.
318 int nc_free_vlen(nc_vlen_t *vl)
320 Free memory comsumed by reading data of a varaible length array
322 type.
323 int nc_put_vlen_element(int ncid, nc_type , void * vlen_element, size_t
325 len, void * data)
326 Write one VLEN.
328 int nc_get_vlen_element(int ncid, nc_type , void ** vlen_element,
330 size_t len, void ** data)
331 Read one VLEN.
333 int nc_free_string(size_t len, char **data)
335 Free memory comsumed by reading data of a string type.
337 int nc_inq_user_type(int ncid, nc_type , char name[], size_t* ,
339 nc_type* , size_t* , int* )
340 Learn about a user define type.
342 int nc_def_enum(int ncid, nc_type base_typeid, const char name[],
344 nc_type* typeidp)
345 Define an enumeration type.
347 int nc_insert_enum(int ncid, nc_type base_typeid, const char name[],
349 const void *value)
350 Insert a name-value pair into enumeration type.
352 int nc_inq_enum_member(int ncid, nc_type xtype, int idx, char name[],
354 void *value)
355 int nc_inq_enum_ident(int ncid, nc_type xtype, int idx, long long val‐
357 ue, char identifier[])
358 Learn about a name-value pair into enumeration type.
360 int nc_def_opaque(int ncid, size_t size, const char name[], nc_type*
362 xtypep)
363 Create an opaque type.
365 int nc_inq_opaque(int ncid, nc_type xtype, char name[], size_t* sizep)
367 Learn about opaque type.
369
373 Users may organize data into hierarchical groups in netCDF-4/HDF5 files
374 (unless NC_CLASSIC_MODEL was used when creating the file).
375 int nc_inq_grps(int ncid, int* numgrps, int ncids[])
377 Learn how many groups (and their ncids) are available from the
379 group represented by ncid.
380 int nc_inq_grpname(int ncid, char name[])
382 int nc_inq_grpname_full(int ncid, size_t* len, char name[])
384 int nc_inq_grpname_len(int ncid, size_t* len)
386 int nc_inq_grp_parent(int ncid, int* ncid)
388 int nc_inq_grp_ncid(int ncid, char name[], int* ncid)
390 int nc_inq_full_ncid(int ncid, char name[], int* ncid)
392 Learn about a group.
394 int nc_inq_varids(int ncid, int* nvars, int* )
396 Get the varids in a group.
398 int nc_inq_dimids(int ncid, int* ndims, int* dimids, int include_par‐
400 ents)
401 Get the dimids in a group and (potentially) its parents.
403 int nc_inq_typeids(int ncid, int* ntypes, int typeids[])
405 Get the typeids of user-defined types in a group.
407 int nc_def_grp(int ncid, char name[], int* ncid)
409 Create a group.
411
413 int nc_inq_dimid(int ncid, const char name[], int* dimid)
414 (Corresponds to ncdimid() in version 2)
416 Given a dimension name, returns the ID of a netCDF dimension in
418 dimid.
419 int nc_inq_dim(int ncid, int dimid, char name[], size_t* len)
421 int nc_inq_dimname(int ncid, int dimid, char name[])
423 int nc_inq_dimlen(int ncid, int dimid, size_t* len)
425 Use these functions to find out about a dimension. If either
427 the name argument or len argument is a NULL pointer, then the
428 associated information will not be returned. Otherwise, name
429 should be big enough (NC_MAX_NAME) to hold the dimension name
430 as the name will be copied into your storage. The length return
431 parameter, len will contain the size of the dimension. For the
432 unlimited dimension, the returned length is the current maximum
433 value used for writing into any of the variables which use the
434 dimension.
435 int nc_rename_dim(int ncid, int dimid, const char name[])
437 (Corresponds to ncdimrename() in version 2)
439 Renames an existing dimension in an open netCDF dataset. If the
441 new name is longer than the old name, the netCDF dataset must be
442 in define mode. You cannot rename a dimension to have the same
443 name as another dimension.
444
446 int nc_def_var(int ncid, const char name[], nc_type xtype, int ndims,
447 const int dimids[], int* varid)
448 (Corresponds to ncvardef() in version 2)
450 Adds a new variable to a netCDF dataset. The netCDF must be in
452 define mode. If not NULL, then varid will be set to the netCDF
453 variable ID.
454 int nc_inq_varid(int ncid, const char name[], int* varid)
456 (Corresponds to ncvarid() in version 2)
458 Returns the ID of a netCDF variable in varid given its name.
460 int nc_inq_var(int ncid, int varid, char name[], nc_type* xtype, int*
462 ndims, int dimids[], int* natts)
463 int nc_inq_varname(int ncid, int varid, char name[])
465 int nc_inq_vartype(int ncid, int varid, nc_type* xtype)
467 int nc_inq_varndims(int ncid, int varid, int* ndims)
469 int nc_inq_vardimid(int ncid, int varid, int dimids[])
471 int nc_inq_varnatts(int ncid, int varid, int* natts)
473 Returns information about a netCDF variable, given its ID. If
475 any of the return parameters (name, xtype, ndims, dimids, or
476 natts) is a NULL pointer, then the corresponding information
477 will not be returned; hence, no space need be allocated for it.
478 int nc_rename_var(int ncid, int varid, const char name[])
480 (Corresponds to ncvarrename() in version 2)
482 Changes the name of a netCDF variable. If the new name is
484 longer than the old name, the netCDF must be in define mode.
485 You cannot rename a variable to have the name of any existing
486 variable.
487
490 The following functions may only be used on variables in a
491 netCDF-4/HDF5 data file. These functions must be called after the vari‐
492 able is defined, but before an enddef call.
493 int nc_def_var_deflate(int ncid, int varid, int shuffle, int deflate,
495 int deflate_level)
496 Turn on compression and/or shuffle filter. (Shuffle filter is only use‐
498 ful for integer data.)
499 int nc_inq_var_deflate(int ncid, int varid, int* shufflep, int* de‐
501 flatep, int* deflate_levelp)
502 Learn about a variable's deflate settings.
504 int nc_def_var_fletcher32(int ncid, int varid, int fletcher32)
506 Turn on checksumming for a variable.
508 int nc_inq_var_fletcher32(int ncid, int varid, int* fletcher32)
510 Learn about checksumming for a variable.
512 int nc_def_var_chunking(int ncid, int varid, int storage, const size_t
514 chunksizesp[])
515 Set chunksizes for a variable.
517 int nc_inq_var_chunking(int ncid, int varid, int* storagep, size_t
519 chunksizesp[])
520 Learn about chunksizes for a variable.
522 int nc_def_var_fill(int ncid, int varid, int no_fill, const size_t
524 chunksizesp[])
525 Set a fill value for a variable.
527 int nc_inq_var_fill(int ncid, int varid, int* storagep, size_t chunk‐
529 sizesp[])
530 Learn the fill value for a variable.
532 int nc_def_var_endian(int ncid, int varid, int endian)
534 Set endianness of variable.
536 int nc_inq_var_endian(int ncid, int varid, int* endianp)
538 Learn the endianness of a variable.
540
545 int nc_put_var_text(int ncid, int varid, const char out[])
546 int nc_put_var_uchar(int ncid, int varid, const unsigned char out[])
548 int nc_put_var_schar(int ncid, int varid, const signed char out[])
550 int nc_put_var_short(int ncid, int varid, const short out[])
552 int nc_put_var_int(int ncid, int varid, const int out[])
554 int nc_put_var_long(int ncid, int varid, const long out[])
556 int nc_put_var_float(int ncid, int varid, const float out[])
558 int nc_put_var_double(int ncid, int varid, const double out[])
560 int nc_put_var_ubyte(int ncid, int varid, const unsigned char out[])
562 int nc_put_var_ushort(int ncid, int varid, const unsigned short out[])
564 int nc_put_var_uint(int ncid, int varid, const unsigned int out[])
566 int nc_put_var_int64(int ncid, int varid, const long long out[])
568 int nc_put_var_uint64(int ncid, int varid, const unsigned long long
570 out[])
571 int nc_put_var_string(int ncid, int varid, const char * out[])
573 Writes an entire netCDF variable (i.e. all the values). The
577 netCDF dataset must be open and in data mode. The type of the
578 data is specified in the function name, and it is converted to
579 the external type of the specified variable, if possible, other‐
580 wise an NC_ERANGE error is returned. Note that rounding is not
581 performed during the conversion. Floating point numbers are
582 truncated when converted to integers.
583 int nc_get_var_text(int ncid, int varid, char in[])
585 int nc_get_var_uchar(int ncid, int varid, unsigned char in[])
587 int nc_get_var_schar(int ncid, int varid, signed char in[])
589 int nc_get_var_short(int ncid, int varid, short in[])
591 int nc_get_var_int(int ncid, int varid, int in[])
593 int nc_get_var_long(int ncid, int varid, long in[])
595 int nc_get_var_float(int ncid, int varid, float in[])
597 int nc_get_var_double(int ncid, int varid, double in[])
599 int nc_get_var_ubyte(int ncid, int varid, unsigned char in[])
601 int nc_get_var_ushort(int ncid, int varid, unsigned short in[])
603 int nc_get_var_uint(int ncid, int varid, unsigned int in[])
605 int nc_get_var_int64(int ncid, int varid, long long in[])
607 int nc_get_var_uint64(int ncid, int varid, unsigned long long in[])
609 int nc_get_var_string(int ncid, int varid, char * in[])
611 Reads an entire netCDF variable (i.e. all the values). The
615 netCDF dataset must be open and in data mode. The data is con‐
616 verted from the external type of the specified variable, if nec‐
617 essary, to the type specified in the function name. If conver‐
618 sion is not possible, an NC_ERANGE error is returned.
619
621 int nc_put_var1_text(int ncid, int varid, const size_t index[], char
622 *out)
623 int nc_put_var1_uchar(int ncid, int varid, const size_t index[], un‐
625 signed char *out)
626 int nc_put_var1_schar(int ncid, int varid, const size_t index[], signed
628 char *out)
629 int nc_put_var1_short(int ncid, int varid, const size_t index[], short
631 *out)
632 int nc_put_var1_int(int ncid, int varid, const size_t index[], int
634 *out)
635 int nc_put_var1_long(int ncid, int varid, const size_t index[], long
637 *out)
638 int nc_put_var1_float(int ncid, int varid, const size_t index[], float
640 *out)
641 int nc_put_var1_double(int ncid, int varid, const size_t index[], dou‐
643 ble *out)
644 int nc_put_var1_ubyte(int ncid, int varid, const size_t index[], un‐
646 signed char *out)
647 int nc_put_var1_ushort(int ncid, int varid, const size_t index[], un‐
649 signed short *out)
650 int nc_put_var1_uint(int ncid, int varid, const size_t index[], un‐
652 signed int *out)
653 int nc_put_var1_int64(int ncid, int varid, const size_t index[], long
655 long *out)
656 int nc_put_var1_uint64(int ncid, int varid, const size_t index[], un‐
658 signed long long *out)
659 int nc_put_var1_string(int ncid, int varid, const size_t index[], char
661 * *out)
662 Puts a single data value into a variable at the position index
666 of an open netCDF dataset that is in data mode. The type of the
667 data is specified in the function name, and it is converted to
668 the external type of the specified variable, if possible, other‐
669 wise an NC_ERANGE error is returned.
670 int nc_get_var1_text(int ncid, int varid, const size_t index[], char*
672 in)
673 int nc_get_var1_uchar(int ncid, int varid, const size_t index[], un‐
675 signed char* in)
676 int nc_get_var1_schar(int ncid, int varid, const size_t index[], signed
678 char* in)
679 int nc_get_var1_short(int ncid, int varid, const size_t index[], short*
681 in)
682 int nc_get_var1_int(int ncid, int varid, const size_t index[], int* in)
684 int nc_get_var1_long(int ncid, int varid, const size_t index[], long*
686 in)
687 int nc_get_var1_float(int ncid, int varid, const size_t index[], float*
689 in)
690 int nc_get_var1_double(int ncid, int varid, const size_t index[], dou‐
692 ble* in)
693 int nc_get_var1_ubyte(int ncid, int varid, const size_t index[], un‐
695 signed char* in)
696 int nc_get_var1_ushort(int ncid, int varid, const size_t index[], un‐
698 signed short* in)
699 int nc_get_var1_uint(int ncid, int varid, const size_t index[], un‐
701 signed int* in)
702 int nc_get_var1_int64(int ncid, int varid, const size_t index[], long
704 long* in)
705 int nc_get_var1_uint64(int ncid, int varid, const size_t index[], un‐
707 signed long long* in)
708 int nc_get_var1_string(int ncid, int varid, const size_t index[], char
710 ** in)
711 Gets a single data value from a variable at the position index
715 of an open netCDF dataset that is in data mode. The data is
716 converted from the external type of the specified variable, if
717 necessary, to the type specified in the function name. If con‐
718 version is not possible, an NC_ERANGE error is returned.
719
721 int nc_put_vara_text(int ncid, int varid, const size_t start[], const
722 size_t count[], const char out[])
723 int nc_put_vara_uchar(int ncid, int varid, const size_t start[], const
725 size_t count[], const unsigned char out[])
726 int nc_put_vara_schar(int ncid, int varid, const size_t start[], const
728 size_t count[], const signed char out[])
729 int nc_put_vara_short(int ncid, int varid, const size_t start[], const
731 size_t count[], const short out[])
732 int nc_put_vara_int(int ncid, int varid, const size_t start[], const
734 size_t count[], const int out[])
735 int nc_put_vara_long(int ncid, int varid, const size_t start[], const
737 size_t count[], const long out[])
738 int nc_put_vara_float(int ncid, int varid, const size_t start[], const
740 size_t count[], const float out[])
741 int nc_put_vara_double(int ncid, int varid, const size_t start[], const
743 size_t count[], const double out[])
744 int nc_put_vara_ubyte(int ncid, int varid, const size_t start[], const
746 size_t count[], const unsigned char out[])
747 int nc_put_vara_ushort(int ncid, int varid, const size_t start[], const
749 size_t count[], const unsigned short out[])
750 int nc_put_vara_uint(int ncid, int varid, const size_t start[], const
752 size_t count[], const unsigned int out[])
753 int nc_put_vara_int64(int ncid, int varid, const size_t start[], const
755 size_t count[], const long long out[])
756 int nc_put_vara_uint64(int ncid, int varid, const size_t start[], const
758 size_t count[], const unsigned long long out[])
759 int nc_put_vara_string(int ncid, int varid, const size_t start[], const
761 size_t count[], const char * out[])
762 Writes an array section of values into a netCDF variable of an
766 open netCDF dataset, which must be in data mode. The array sec‐
767 tion is specified by the start and count vectors, which give the
768 starting index and count of values along each dimension of the
769 specified variable. The type of the data is specified in the
770 function name and is converted to the external type of the spec‐
771 ified variable, if possible, otherwise an NC_ERANGE error is re‐
772 turned.
773 int nc_get_vara_text(int ncid, int varid, const size_t start[], const
775 size_t count[], char in[])
776 int nc_get_vara_uchar(int ncid, int varid, const size_t start[], const
778 size_t count[], unsigned char in[])
779 int nc_get_vara_schar(int ncid, int varid, const size_t start[], const
781 size_t count[], signed char in[])
782 int nc_get_vara_short(int ncid, int varid, const size_t start[], const
784 size_t count[], short in[])
785 int nc_get_vara_int(int ncid, int varid, const size_t start[], const
787 size_t count[], int in[])
788 int nc_get_vara_long(int ncid, int varid, const size_t start[], const
790 size_t count[], long in[])
791 int nc_get_vara_float(int ncid, int varid, const size_t start[], const
793 size_t count[], float in[])
794 int nc_get_vara_double(int ncid, int varid, const size_t start[], const
796 size_t count[], double in[])
797 int nc_get_vara_ubyte(int ncid, int varid, const size_t start[], const
799 size_t count[], unsigned char in[])
800 int nc_get_vara_ushort(int ncid, int varid, const size_t start[], const
802 size_t count[], unsigned short in[])
803 int nc_get_vara_uint(int ncid, int varid, const size_t start[], const
805 size_t count[], unsigned int in[])
806 int nc_get_vara_int64(int ncid, int varid, const size_t start[], const
808 size_t count[], long long in[])
809 int nc_get_vara_uint64(int ncid, int varid, const size_t start[], const
811 size_t count[], unsigned long long in[])
812 int nc_get_vara_string(int ncid, int varid, const size_t start[], const
814 size_t count[], char * in[])
815 Reads an array section of values from a netCDF variable of an
819 open netCDF dataset, which must be in data mode. The array sec‐
820 tion is specified by the start and count vectors, which give the
821 starting index and count of values along each dimension of the
822 specified variable. The data is converted from the external
823 type of the specified variable, if necessary, to the type speci‐
824 fied in the function name. If conversion is not possible, an
825 NC_ERANGE error is returned.
826
828 int nc_put_vars_text(int ncid, int varid, const size_t start[], const
829 size_t count[], const size_t stride[], const char out[])
830 int nc_put_vars_uchar(int ncid, int varid, const size_t start[], const
832 size_t count[], const size_t stride[], const unsigned char
833 out[])
834 int nc_put_vars_schar(int ncid, int varid, const size_t start[], const
836 size_t count[], const size_t stride[], const signed char out[])
837 int nc_put_vars_short(int ncid, int varid, const size_t start[], const
839 size_t count[], const size_t stride[], const short out[])
840 int nc_put_vars_int(int ncid, int varid, const size_t start[], const
842 size_t count[], const size_t stride[], const int out[])
843 int nc_put_vars_long(int ncid, int varid, const size_t start[], const
845 size_t count[], const size_t stride[], const long out[])
846 int nc_put_vars_float(int ncid, int varid, const size_t start[], const
848 size_t count[], const size_t stride[], const float out[])
849 int nc_put_vars_double(int ncid, int varid, const size_t start[], const
851 size_t count[], const size_t stride[], const double out[])
852 int nc_put_vars_ubyte(int ncid, int varid, const size_t start[], const
854 size_t count[], const size_t stride[], const unsigned char
855 out[])
856 int nc_put_vars_ushort(int ncid, int varid, const size_t start[], const
858 size_t count[], const size_t stride[], const unsigned short
859 out[])
860 int nc_put_vars_uint(int ncid, int varid, const size_t start[], const
862 size_t count[], const size_t stride[], const unsigned int out[])
863 int nc_put_vars_int64(int ncid, int varid, const size_t start[], const
865 size_t count[], const size_t stride[], const long long out[])
866 int nc_put_vars_uint64(int ncid, int varid, const size_t start[], const
868 size_t count[], const size_t stride[], const unsigned long long
869 out[])
870 int nc_put_vars_string(int ncid, int varid, const size_t start[], const
872 size_t count[], const size_t stride[], const char * out[])
873 These functions are used for strided output, which is like the
877 array section output described above, except that the sampling
878 stride (the interval between accessed values) is specified for
879 each dimension. For an explanation of the sampling stride vec‐
880 tor, see COMMON ARGUMENTS DESCRIPTIONS below.
881 int nc_get_vars_text(int ncid, int varid, const size_t start[], const
883 size_t count[], const size_t stride[], char in[])
884 int nc_get_vars_uchar(int ncid, int varid, const size_t start[], const
886 size_t count[], const size_t stride[], unsigned char in[])
887 int nc_get_vars_schar(int ncid, int varid, const size_t start[], const
889 size_t count[], const size_t stride[], signed char in[])
890 int nc_get_vars_short(int ncid, int varid, const size_t start[], const
892 size_t count[], const size_t stride[], short in[])
893 int nc_get_vars_int(int ncid, int varid, const size_t start[], const
895 size_t count[], const size_t stride[], int in[])
896 int nc_get_vars_long(int ncid, int varid, const size_t start[], const
898 size_t count[], const size_t stride[], long in[])
899 int nc_get_vars_float(int ncid, int varid, const size_t start[], const
901 size_t count[], const size_t stride[], float in[])
902 int nc_get_vars_double(int ncid, int varid, const size_t start[], const
904 size_t count[], const size_t stride[], double in[])
905 int nc_get_vars_ubyte(int ncid, int varid, const size_t start[], const
907 size_t count[], const size_t stride[], unsigned char in[])
908 int nc_get_vars_ushort(int ncid, int varid, const size_t start[], const
910 size_t count[], const size_t stride[], unsigned short in[])
911 int nc_get_vars_uint(int ncid, int varid, const size_t start[], const
913 size_t count[], const size_t stride[], unsigned int in[])
914 int nc_get_vars_int64(int ncid, int varid, const size_t start[], const
916 size_t count[], const size_t stride[], long long in[])
917 int nc_get_vars_uint64(int ncid, int varid, const size_t start[], const
919 size_t count[], const size_t stride[], unsigned long long in[])
920 int nc_get_vars_string(int ncid, int varid, const size_t start[], const
922 size_t count[], const size_t stride[], char * in[])
923 These functions are used for strided input, which is like the
927 array section input described above, except that the sampling
928 stride (the interval between accessed values) is specified for
929 each dimension. For an explanation of the sampling stride vec‐
930 tor, see COMMON ARGUMENTS DESCRIPTIONS below.
931
933 int nc_put_varm_text(int ncid, int varid, const size_t start[], const
934 size_t count[], const size_t stride[], imap, const char out[])
935 int nc_put_varm_uchar(int ncid, int varid, const size_t start[], const
937 size_t count[], const size_t stride[], imap, const unsigned char
938 out[])
939 int nc_put_varm_schar(int ncid, int varid, const size_t start[], const
941 size_t count[], const size_t stride[], imap, const signed char
942 out[])
943 int nc_put_varm_short(int ncid, int varid, const size_t start[], const
945 size_t count[], const size_t stride[], imap, const short out[])
946 int nc_put_varm_int(int ncid, int varid, const size_t start[], const
948 size_t count[], const size_t stride[], imap, const int out[])
949 int nc_put_varm_long(int ncid, int varid, const size_t start[], const
951 size_t count[], const size_t stride[], imap, const long out[])
952 int nc_put_varm_float(int ncid, int varid, const size_t start[], const
954 size_t count[], const size_t stride[], imap, const float out[])
955 int nc_put_varm_double(int ncid, int varid, const size_t start[], const
957 size_t count[], const size_t stride[], imap, const double out[])
958 int nc_put_varm_ubyte(int ncid, int varid, const size_t start[], const
960 size_t count[], const size_t stride[], imap, const unsigned char
961 out[])
962 int nc_put_varm_ushort(int ncid, int varid, const size_t start[], const
964 size_t count[], const size_t stride[], imap, const unsigned
965 short out[])
966 int nc_put_varm_uint(int ncid, int varid, const size_t start[], const
968 size_t count[], const size_t stride[], imap, const unsigned int
969 out[])
970 int nc_put_varm_int64(int ncid, int varid, const size_t start[], const
972 size_t count[], const size_t stride[], imap, const long long
973 out[])
974 int nc_put_varm_uint64(int ncid, int varid, const size_t start[], const
976 size_t count[], const size_t stride[], imap, const unsigned long
977 long out[])
978 int nc_put_varm_string(int ncid, int varid, const size_t start[], const
980 size_t count[], const size_t stride[], imap, const char * out[])
981 These functions are used for mapped output, which is like strid‐
985 ed output described above, except that an additional index map‐
986 ping vector is provided to specify the in-memory arrangement of
987 the data values. For an explanation of the index mapping vec‐
988 tor, see COMMON ARGUMENTS DESCRIPTIONS below.
989 int nc_get_varm_text(int ncid, int varid, const size_t start[], const
991 size_t count[], const size_t stride[], imap, char in[])
992 int nc_get_varm_uchar(int ncid, int varid, const size_t start[], const
994 size_t count[], const size_t stride[], imap, unsigned char in[])
995 int nc_get_varm_schar(int ncid, int varid, const size_t start[], const
997 size_t count[], const size_t stride[], imap, signed char in[])
998 int nc_get_varm_short(int ncid, int varid, const size_t start[], const
1000 size_t count[], const size_t stride[], imap, short in[])
1001 int nc_get_varm_int(int ncid, int varid, const size_t start[], const
1003 size_t count[], const size_t stride[], imap, int in[])
1004 int nc_get_varm_long(int ncid, int varid, const size_t start[], const
1006 size_t count[], const size_t stride[], imap, long in[])
1007 int nc_get_varm_float(int ncid, int varid, const size_t start[], const
1009 size_t count[], const size_t stride[], imap, float in[])
1010 int nc_get_varm_double(int ncid, int varid, const size_t start[], const
1012 size_t count[], const size_t stride[], imap, double in[])
1013 int nc_get_varm_ubyte(int ncid, int varid, const size_t start[], const
1015 size_t count[], const size_t stride[], imap, unsigned char in[])
1016 int nc_get_varm_ushort(int ncid, int varid, const size_t start[], const
1018 size_t count[], const size_t stride[], imap, unsigned short
1019 in[])
1020 int nc_get_varm_uint(int ncid, int varid, const size_t start[], const
1022 size_t count[], const size_t stride[], imap, unsigned int in[])
1023 int nc_get_varm_int64(int ncid, int varid, const size_t start[], const
1025 size_t count[], const size_t stride[], imap, long long in[])
1026 int nc_get_varm_uint64(int ncid, int varid, const size_t start[], const
1028 size_t count[], const size_t stride[], imap, unsigned long long
1029 in[])
1030 int nc_get_varm_string(int ncid, int varid, const size_t start[], const
1032 size_t count[], const size_t stride[], imap, char * in[])
1033 These functions are used for mapped input, which is like strided
1037 input described above, except that an additional index mapping
1038 vector is provided to specify the in-memory arrangement of the
1039 data values. For an explanation of the index mapping vector,
1040 see COMMON ARGUMENTS DESCRIPTIONS below.
1041
1043 int nc_put_att_text(int ncid, int varid, const char name[], nc_type
1044 xtype, size_t len, const char out[])
1045 int nc_put_att_uchar(int ncid, int varid, const char name[], nc_type
1047 xtype, size_t len, const unsigned char out[])
1048 int nc_put_att_schar(int ncid, int varid, const char name[], nc_type
1050 xtype, size_t len, const signed char out[])
1051 int nc_put_att_short(int ncid, int varid, const char name[], nc_type
1053 xtype, size_t len, const short out[])
1054 int nc_put_att_int(int ncid, int varid, const char name[], nc_type
1056 xtype, size_t len, const int out[])
1057 int nc_put_att_long(int ncid, int varid, const char name[], nc_type
1059 xtype, size_t len, const long out[])
1060 int nc_put_att_float(int ncid, int varid, const char name[], nc_type
1062 xtype, size_t len, const float out[])
1063 int nc_put_att_double(int ncid, int varid, const char name[], nc_type
1065 xtype, size_t len, const double out[])
1066 int nc_put_att_ubyte(int ncid, int varid, const char name[], nc_type
1068 xtype, size_t len, const unsigned char out[])
1069 int nc_put_att_ushort(int ncid, int varid, const char name[], nc_type
1071 xtype, size_t len, const unsigned short out[])
1072 int nc_put_att_uint(int ncid, int varid, const char name[], nc_type
1074 xtype, size_t len, const unsigned int out[])
1075 int nc_put_att_int64(int ncid, int varid, const char name[], nc_type
1077 xtype, size_t len, const long long out[])
1078 int nc_put_att_uint64(int ncid, int varid, const char name[], nc_type
1080 xtype, size_t len, const unsigned long long out[])
1081 int nc_put_att_string(int ncid, int varid, const char name[], nc_type
1083 xtype, size_t len, const char * out[])
1084 int nc_put_att(int ncid, int varid, const char name[], nc_type xtype,
1088 size_t len, void * ip)
1089 int nc_get_att(int ncid, int varid, const char name[], void ** ip)
1091 Unlike variables, attributes do not have separate functions for
1093 defining and writing values. This family of functions defines a
1094 new attribute with a value or changes the value of an existing
1095 attribute. If the attribute is new, or if the space required to
1096 store the attribute value is greater than before, the netCDF
1097 dataset must be in define mode. The parameter len is the number
1098 of values from out to transfer. It is often one, except that
1099 for nc_put_att_text() it will usually be strlen(out).
1100 For these functions, the type component of the function name
1102 refers to the in-memory type of the value, whereas the xtype ar‐
1103 gument refers to the external type for storing the value. An
1104 NC_ERANGE error results if a conversion between these types is
1105 not possible. In this case the value is represented with the
1106 appropriate fill-value for the associated external type.
1107 int nc_inq_attname(int ncid, int varid, int attnum, char name[])
1109 Gets the name of an attribute, given its variable ID and at‐
1111 tribute number. This function is useful in generic applications
1112 that need to get the names of all the attributes associated with
1113 a variable, since attributes are accessed by name rather than
1114 number in all other attribute functions. The number of an at‐
1115 tribute is more volatile than the name, since it can change when
1116 other attributes of the same variable are deleted. The at‐
1117 tributes for each variable are numbered from 0 (the first at‐
1118 tribute) to nvatts-1, where nvatts is the number of attributes
1119 for the variable, as returned from a call to nc_inq_varnatts().
1120 If the name parameter is a NULL pointer, no name will be re‐
1121 turned and no space need be allocated.
1122 int nc_inq_att(int ncid, int varid, const char name[], nc_type* xtype,
1124 size_t* len)
1125 int nc_inq_attid(int ncid, int varid, const char name[], int* attnum)
1127 int nc_inq_atttype(int ncid, int varid, const char name[], nc_type*
1129 xtype)
1130 int nc_inq_attlen(int ncid, int varid, const char name[], size_t* len)
1132 These functions return information about a netCDF attribute,
1134 given its variable ID and name. The information returned is the
1135 external type in xtype and the number of elements in the at‐
1136 tribute as len. If any of the return arguments is a NULL point‐
1137 er, the specified information will not be returned.
1138 int nc_copy_att(int ncid, int varid_in, const char name[], int
1140 ncid_out, int varid_out)
1141 Copies an attribute from one netCDF dataset to another. It can
1143 also be used to copy an attribute from one variable to another
1144 within the same netCDF. ncid_in is the netCDF ID of an input
1145 netCDF dataset from which the attribute will be copied.
1146 varid_in is the ID of the variable in the input netCDF dataset
1147 from which the attribute will be copied, or NC_GLOBAL for a
1148 global attribute. name is the name of the attribute in the in‐
1149 put netCDF dataset to be copied. ncid_out is the netCDF ID of
1150 the output netCDF dataset to which the attribute will be copied.
1151 It is permissible for the input and output netCDF ID's to be the
1152 same. The output netCDF dataset should be in define mode if the
1153 attribute to be copied does not already exist for the target
1154 variable, or if it would cause an existing target attribute to
1155 grow. varid_out is the ID of the variable in the output netCDF
1156 dataset to which the attribute will be copied, or NC_GLOBAL to
1157 copy to a global attribute.
1158 int nc_rename_att(int ncid, int varid, const char name[], const char
1160 newname[])
1161 Changes the name of an attribute. If the new name is longer
1163 than the original name, the netCDF must be in define mode. You
1164 cannot rename an attribute to have the same name as another at‐
1165 tribute of the same variable. name is the original attribute
1166 name. newname is the new name to be assigned to the specified
1167 attribute. If the new name is longer than the old name, the
1168 netCDF dataset must be in define mode.
1169 int nc_del_att(int ncid, int varid, const char name[])
1171 Deletes an attribute from a netCDF dataset. The dataset must be
1173 in define mode.
1174 int nc_get_att_text(int ncid, int varid, const char name[], char in[])
1176 int nc_get_att_uchar(int ncid, int varid, const char name[], unsigned
1178 char in[])
1179 int nc_get_att_schar(int ncid, int varid, const char name[], signed
1181 char in[])
1182 int nc_get_att_short(int ncid, int varid, const char name[], short
1184 in[])
1185 int nc_get_att_int(int ncid, int varid, const char name[], int in[])
1187 int nc_get_att_long(int ncid, int varid, const char name[], long in[])
1189 int nc_get_att_float(int ncid, int varid, const char name[], float
1191 in[])
1192 int nc_get_att_double(int ncid, int varid, const char name[], double
1194 in[])
1195 int nc_get_att_ubyte(int ncid, int varid, const char name[], unsigned
1197 char in[])
1198 int nc_get_att_ushort(int ncid, int varid, const char name[], unsigned
1200 short in[])
1201 int nc_get_att_uint(int ncid, int varid, const char name[], unsigned
1203 int in[])
1204 int nc_get_att_int64(int ncid, int varid, const char name[], long long
1206 in[])
1207 int nc_get_att_uint64(int ncid, int varid, const char name[], unsigned
1209 long long in[])
1210 int nc_get_att_string(int ncid, int varid, const char name[], char *
1212 in[])
1213 Gets the value(s) of a netCDF attribute, given its variable ID
1217 and name. Converts from the external type to the type specified
1218 in the function name, if possible, otherwise returns an
1219 NC_ERANGE error. All elements of the vector of attribute values
1220 are returned, so you must allocate enough space to hold them.
1221 If you don't know how much space to reserve, call nc_inq_at‐
1222 tlen() first to find out the length of the attribute.
1223
1225 In this section we define some common arguments which are used in the
1226 "FUNCTION DESCRIPTIONS" section.
1227 int ncid
1229 is the netCDF ID returned from a previous, successful call to
1230 nc_open() or nc_create()
1231 char name[]
1233 is the name of a dimension, variable, or attribute. The names of
1234 dimensions, variables and attributes consist of arbitrary se‐
1235 quences of alphanumeric characters (as well as underscore '_',
1236 period '.' and hyphen '-'), beginning with a letter or under‐
1237 score. (However names commencing with underscore are reserved
1238 for system use.) Case is significant in netCDF names. A zero-
1239 length name is not allowed. As an input argument, it shall be a
1240 pointer to a 0-terminated string; as an output argument, it
1241 shall be the address of a buffer in which to hold such a string.
1242 The maximum allowable number of characters (excluding the termi‐
1243 nating 0) is NC_MAX_NAME.
1244 nc_type xtype
1246 specifies the external data type of a netCDF variable or at‐
1247 tribute and is one of the following: NC_BYTE, NC_CHAR, NC_SHORT,
1248 NC_INT, NC_FLOAT, or NC_DOUBLE. These are used to specify 8-bit
1249 integers, characters, 16-bit integers, 32-bit integers, 32-bit
1250 IEEE floating point numbers, and 64-bit IEEE floating-point num‐
1251 bers, respectively. (NC_INT corresponds to NC_LONG in version
1252 2, to specify a 32-bit integer).
1253 int dimids[]
1255 is a vector of dimension ID's and defines the shape of a netCDF
1256 variable. The size of the vector shall be greater than or equal
1257 to the rank (i.e. the number of dimensions) of the variable
1258 (ndims). The vector shall be ordered by the speed with which a
1259 dimension varies: dimids[ndims-1] shall be the dimension ID of
1260 the most rapidly varying dimension and dimids[0] shall be the
1261 dimension ID of the most slowly varying dimension. The maximum
1262 possible number of dimensions for a variable is given by the
1263 symbolic constant NC_MAX_VAR_DIMS.
1264 int dimid
1266 is the ID of a netCDF dimension. netCDF dimension ID's are al‐
1267 located sequentially from the non-negative integers beginning
1268 with 0.
1269 int ndims
1271 is either the total number of dimensions in a netCDF dataset or
1272 the rank (i.e. the number of dimensions) of a netCDF variable.
1273 The value shall not be negative or greater than the symbolic
1274 constant NC_MAX_VAR_DIMS.
1275 int varid
1277 is the ID of a netCDF variable or (for the attribute-access
1278 functions) the symbolic constant NC_GLOBAL, which is used to
1279 reference global attributes. netCDF variable ID's are allocated
1280 sequentially from the non-negative integers beginning with 0.
1281 int* natts
1283 is the number of global attributes in a netCDF dataset for the
1284 nc_inquire() function or the number of attributes associated
1285 with a netCDF variable for the nc_varinq() function.
1286 const size_t index[]
1288 specifies the indicial coordinates of the netCDF data value to
1289 be accessed. The indices start at 0; thus, for example, the
1290 first data value of a two-dimensional variable is (0,0). The
1291 size of the vector shall be at least the rank of the associated
1292 netCDF variable and its elements shall correspond, in order, to
1293 the variable's dimensions.
1294 const size_t start[]
1296 specifies the starting point for accessing a netCDF variable's
1297 data values in terms of the indicial coordinates of the corner
1298 of the array section. The indices start at 0; thus, the first
1299 data value of a variable is (0, 0, ..., 0). The size of the
1300 vector shall be at least the rank of the associated netCDF vari‐
1301 able and its elements shall correspond, in order, to the vari‐
1302 able's dimensions.
1303 const size_t count[]
1305 specifies the number of indices selected along each dimension of
1306 the array section. Thus, to access a single value, for example,
1307 specify count as (1, 1, ..., 1). Note that, for strided I/O,
1308 this argument must be adjusted to be compatible with the stride
1309 and start arguments so that the interaction of the three does
1310 not attempt to access an invalid data co-ordinate. The elements
1311 of the count vector correspond, in order, to the variable's di‐
1312 mensions.
1313 const size_t stride[]
1315 specifies the sampling interval along each dimension of the
1316 netCDF variable. The elements of the stride vector correspond,
1317 in order, to the netCDF variable's dimensions (stride[0]) gives
1318 the sampling interval along the most slowly varying dimension of
1319 the netCDF variable). Sampling intervals are specified in type-
1320 independent units of elements (a value of 1 selects consecutive
1321 elements of the netCDF variable along the corresponding dimen‐
1322 sion, a value of 2 selects every other element, etc.). A NULL
1323 stride argument is treated as (1, 1, ... , 1).
1324 imap specifies the mapping between the dimensions of a netCDF vari‐
1326 able and the in-memory structure of the internal data array.
1327 The elements of the index mapping vector correspond, in order,
1328 to the netCDF variable's dimensions (imap[0] gives the distance
1329 between elements of the internal array corresponding to the most
1330 slowly varying dimension of the netCDF variable). Distances be‐
1331 tween elements are specified in type-independent units of ele‐
1332 ments (the distance between internal elements that occupy adja‐
1333 cent memory locations is 1 and not the element's byte-length as
1334 in netCDF 2). A NULL pointer means the memory-resident values
1335 have the same structure as the associated netCDF variable.
1336
1338 By default, the netCDF interface sets the values of all newly-defined
1339 variables of finite length (i.e. those that do not have an unlimited,
1340 dimension) to the type-dependent fill-value associated with each vari‐
1341 able. This is done when nc_enddef() is called. The fill-value for a
1342 variable may be changed from the default value by defining the at‐
1343 tribute `_FillValue' for the variable. This attribute must have the
1344 same type as the variable and be of length one.
1345 Variables with an unlimited dimension are also prefilled, but on an `as
1347 needed' basis. For example, if the first write of such a variable is
1348 to position 5, then positions 0 through 4 (and no others) would be set
1349 to the fill-value at the same time.
1350 This default prefilling of data values may be disabled by or'ing the
1352 NC_NOFILL flag into the mode parameter of nc_open() or nc_create(), or,
1353 by calling the function nc_set_fill() with the argument NC_NOFILL. For
1354 variables that do not use the unlimited dimension, this call must be
1355 made before nc_enddef(). For variables that use the unlimited dimen‐
1356 sion, this call may be made at any time.
1357 One can obtain increased performance of the netCDF interface by using
1359 this feature, but only at the expense of requiring the application to
1360 set every single data value. The performance enhancing behavior of
1361 this function is dependent on the particulars of the implementation and
1362 dataset format. The flag value controlled by nc_set_fill() is per
1363 netCDF ID, not per variable or per write. Allowing this to change af‐
1364 fects the degree to which a program can be effectively parallelized.
1365 Given all of this, we state that the use of this feature may not be
1366 available (or even needed) in future releases. Programmers are cau‐
1367 tioned against heavy reliance upon this feature.
1368 int nc_setfill(int ncid, int fillmode, int* old_fillemode)
1370 (Corresponds to ncsetfill() in version 2)
1372 Determines whether or not variable prefilling will be done (see
1374 above). The netCDF dataset shall be writable. fillmode is ei‐
1375 ther NC_FILL to enable prefilling (the default) or NC_NOFILL to
1376 disable prefilling. This function returns the previous setting
1377 in old_fillmode.
1378
1383 Additional functions for use on SGI/Cray MPP machines (_CRAYMPP).
1384 These are used to set and inquire which PE is the base for MPP for a
1385 particular netCDF. These are only relevant when using the SGI/Cray
1386 ``global'' Flexible File I/O layer and desire to have only a subset of
1387 PEs to open the specific netCDF file. For technical reasons, these
1388 functions are available on all platforms. On a platform other than
1389 SGI/Cray MPP, it is as if only processor available were processor 0.
1390 To use this feature, you need to specify a communicator group and call
1392 glio_group_mpi() or glio_group_shmem() prior to the netCDF nc_open()
1393 and nc_create() calls.
1394 int nc__create_mp(const char path[], int cmode, size_t initialsize, int
1396 pe, size_t* chunksize, int* ncid)
1397 Like nc__create() but allows the base PE to be set.
1399 The argument pe sets the base PE at creation time. In the MPP
1401 environment, nc__create() and nc_create() set the base PE to
1402 processor zero by default.
1403 int nc__open_mp(const char path[], int mode, int pe, size_t* chunksize,
1405 int* ncid)
1406 Like nc__open() but allows the base PE to be set. The argument
1408 pe sets the base PE at creation time. In the MPP environment,
1409 nc__open() and nc_open() set the base PE to processor zero by
1410 default.
1411 int nc_inq_base_pe(int ncid, int* pe)
1413 Inquires of the netCDF dataset which PE is being used as the
1415 base for MPP use. This is safe to use at any time.
1416 int nc_set_base_pe(int ncid, int pe)
1418 Resets the base PE for the netCDF dataset. Only perform this
1420 operation when the affected communicator group synchronizes be‐
1421 fore and after the call. This operation is very risky and
1422 should only be contemplated under only the most extreme cases.
1423
1425 NETCDF_FFIOSPEC
1426 Specifies the Flexible File I/O buffers for netCDF I/O when execut‐
1427 ing under the UNICOS operating system (the variable is ignored on
1428 other operating systems). An appropriate specification can greatly
1429 increase the efficiency of netCDF I/O -- to the extent that it can
1430 actually surpass FORTRAN binary I/O. This environment variable has
1431 been made a little more generalized, such that other FFIO option
1432 specifications can now be added. The default specification is bu‐
1433 fa:336:2, unless a current FFIO specification is in operation,
1434 which will be honored. See UNICOS Flexible File I/O for more in‐
1435 formation.
1436
1438 Both a mailing list and a digest are available for discussion of the
1439 netCDF interface and announcements about netCDF bugs, fixes, and en‐
1440 hancements. To begin or change your subscription to either the mail‐
1441 ing-list or the digest, send one of the following in the body (not the
1442 subject line) of an email message to "majordomo@unidata.ucar.edu". Use
1443 your email address in place of jdoe@host.inst.domain.
1444 To subscribe to the netCDF mailing list:
1446 subscribe netcdfgroup jdoe@host.inst.domain
1447 To unsubscribe from the netCDF mailing list:
1448 unsubscribe netcdfgroup jdoe@host.inst.domain
1449 To subscribe to the netCDF digest:
1450 subscribe netcdfdigest jdoe@host.inst.domain
1451 To unsubscribe from the netCDF digest:
1452 unsubscribe netcdfdigest jdoe@host.inst.domain
1453 To retrieve the general introductory information for the mailing list:
1454 info netcdfgroup
1455 To get a synopsis of other majordomo commands:
1456 help
1457
1459 ncdump(1), ncgen(1), netcdf(3).
1460 netCDF User's Guide, published by the Unidata Program Center, Universi‐
1462 ty Corporation for Atmospheric Research, located in Boulder, Colorado.
1463 NetCDF home page at http:/www.unidata.ucar.edu/netcdf.
1465Printed: 2019-06-22 1997-04-18 NETCDF(3)