hdfv

Gateway to HDF Vgroup (V) interface

Syntax

[out1,...,outN] = hdfv(funcstr,input1,...,inputN)

Description

hdfv is the MATLAB^® gateway to the HDF Vgroup (V) interface.

[out1,...,outN] = hdfv(funcstr,input1,...,inputN) returns one or more outputs corresponding to the V function in the HDF library specified by functstr.

There is a one-to-one correspondence between V functions in the HDF library and valid values for funcstr. For example, hdfv('nattrs',vgroup_id) corresponds to the C library call Vnattrs(vgroup_id).

Access Functions

Access functions open files, initialize the Vgroup interface, and access individual groups. They also terminate access to vgroups and the Vgroup interface and close HDF files.

Value of `funcstr`	Function Syntax	Description
`'start'`	`status = hdfv('start',file_id)`	Initializes the V interface.
`'attach'`	`vgroup_id = hdfv('attach',file_id,vgroup_ref,access)`	Establishes access to a vgroup. `access` can be `'r'` or `'w'`.
`'detach'`	`status = hdfv('detach',vgroup_id)`	Terminates access to a vgroup.
`'end'`	`status = hdfv('end',file_id)`	Terminates access to the V interface.

Create Functions

Create functions organize, label, and add data objects to vgroups.

Value of `funcstr`	Function Syntax	Description
`'setclass'`	`status = hdfv('setclass',vgroup_id,class)`	Assigns a class to a vgroup.
`'setname'`	`status = hdfv('setname',vgroup_id,name)`	Assigns a name to a vgroup.
`'insert'`	`ref = hdfv('insert',vgroup_id, id)`	Adds a vgroup or vdata to an existing group. `id` can be a vdata id or a vgroup id.
`'addtagref'`	`status = hdfv('addtagref',vgroup_id,tag,ref)`	Adds any HDF data object to an existing vgroup.
`'setattr'`	`status = hdfv('setattr',vgroup_id,name,A)`	Sets the attribute of a vgroup.

File Inquiry Functions

File inquiry functions return information about how vgroups are stored in a file. They are useful for locating vgroups in a file.

Value of `funcstr`	Function Syntax	Description
`'lone'`	`[refs,count] = hdfv('lone',file_id,maxsize)`	Returns the reference numbers of vgroups not included in other vgroups.
`'getid'`	`next_ref = hdfv('getid',file_id,vgroup_ref)`	Returns the reference number for the next vgroup in the HDF file.
`'find'`	`vgroup_ref = hdfv('find',file_id,vgroup_name)`	Returns the reference number of the vgroup with the specified name if successful and zero otherwise.
`'findclass'`	`vgroup_ref = hdfv('findclass',file_id,class)`	Returns the reference number of the vgroup with the specified class.

Vgroup Inquiry Functions

Vgroup inquiry functions provide specific information about a specific vgroup. This information includes the class, name, member count, and additional member information.

Value of `funcstr`	Function Syntax	Description
`'getclass'`	`[class_name,status] = hdfv('getclass',vgroup_id)`	Returns the name of the class of the specified group.
`'getname'`	`[vgroup_name,status] = hdfv('getname',vgroup_id)`	Returns the name of the specified group.
`'inquire'`	`[num_entries,name,status] = hdfv('inquire',vgroup_id)`	Returns the number of entries and the name of a vgroup.
`'isvg'`	`status = hdfv('isvg',vgroup_id,ref)`	Checks if the object specified by ref refers to a child vgroup of the vgroup specified by `vgroup_id`.
`'isvs'`	`status = hdfv('isvs',vgroup_id,vdata_ref)`	Checks if the object specified by `vdata_ref` refers to a child vdata of the vgroup specified by `vgroup_id`.
`'gettagref'`	`[tag,ref,status] = hdfv('gettagref',vgroup_id,index)`	Retrieves a tag/reference number pair for a data object in the specified vgroup.
`'ntagrefs'`	`count = hdfv('ntagrefs',vgroup_id)`	Returns the number of tag/reference number pairs contained in the specified vgroup.
`'gettagrefs'`	`[tag,refs,count] = hdfv('gettagrefs',vgroup_id,maxsize)`	Retrieves the tag/reference pairs of all the data objects within a vgroup.
`'inqtagref'`	`tf = hdfv('inqtagref',vgroup_id,tag,ref)`	Checks if an object belongs to a vgroup.
`'getversion'`	`version = hdfv('getversion',vgroup_id)`	Queries the vgroup version of a given vgroup.
`'nattrs'`	`count = hdfv('nattrs',vgroup_id)`	Queries the total number of vgroup attributes.
`'attrinfo'`	`[name,data_type,count,nbytes,status] = hdfv('attrinfo',vgroup_id,... attr_index)`	Queries information on a given vgroup attribute.
`'getattr'`	`[values,status] = hdfv('getattr',vgroup_id,attr_index)`	Queries the values of a given attribute.
`'Queryref'`	`ref = hdfv('Queryref',vgroup_id)`	Returns the reference number of the specified vgroup.
`'Querytag'`	`tag = hdfv('Querytag',vgroup_id)`	Returns the tag of the specified vgroup.
`'flocate'`	`vdata_ref = hdfv('flocate',vgroup_id,field)`	Returns the reference number of the vdata containing the specified field name in the specified vgroup.
`'nrefs'`	`count = hdfv('nrefs',vgroup_id,tag)`	Returns the number of data objects with the specified tag in the specified vgroup.

Output Arguments

A status or identifier output of -1 indicates that the operation failed.

Version History

Introduced before R2006a