hdfvs

Gateway to VS functions in HDF Vdata interface

Syntax

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

Description

hdfvs is the MATLAB^® gateway to the VS functions in the HDF Vdata interface.

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

There is a one-to-one correspondence between VS functions in the HDF library and valid values for funcstr. For example, hdfvs('detach',vdata_id) corresponds to the C library call VSdetach(vdata_id).

Access Functions

Access functions attach, or allow access, to vdatas. Data transfer can only occur after a vdata has been accessed. These routines also detach from, or properly terminate access to, vdatas when data transfer has been completed.

Value of `funcstr`	Function Syntax	Description
`'attach'`	`vdata_id = hdfvs('attach',file_id,vdata_ref,access)`	Establishes access to a specified vdata. `access` can be `'r'` or `'w'`.
`'detach'`	`status = hdfvs('detach',vdata_id)`	Terminates access to a specified vdata.

Read and Write Functions

Read and write functions read and write the contents of a vdata.

Value of `funcstr`	Function Syntax	Description
`'fdefine'`	`status = hdfvs('fdefine',vdata_id,fieldname,data_type,order)`	Defines a new vdata field. `data_type` is character vector or string scalar containing the HDF number type. Specify `data_type` as one of these values: `'uchar8'`, `'uchar'`, `'char8'`, `'char'`, `'double'`, `'uint8'`, `'uint16'`, `'uint32'`, `'float'`, `'int8'`, `'int16'`, or `'int32'`.
`'setclass'`	`status = hdfvs('setclass',vdata_id,class)`	Assigns a class to a vdata.
`'setfields'`	`status = hdfvs('setfields',vdata_id,fields)`	Specifies the vdata fields to be written.
`'setinterlace'`	`status = hdfvs('setinterlace',vdata_id,interlace)`	Sets the interlace mode for a vdata. `interlace` can be `'full'` or `'no'`.
`'setname'`	`status = hdfvs('setname',vdata_id,name)`	Assigns a name to a vdata.
`'write'`	`count = hdfvs('write', vdata_id, data)`	Writes to a vdata. data must be an `nfields`-by-1 cell array. Each cell must contain an `order(i)`-by-`n` vector of data where `order(i)` is the number of scalar values in each field. The types of the data must match the field types set via `hdfvs('setfields')` or the fields in an already existing vdata.
`'read'`	`[data,count] = hdfvs('read',vdata_id,n)`	Reads from a vdata. Data is returned in a `nfields`-by-1 cell array. Each cell contains a `order(i)`-by-`n` vector of data where `order` is the number of scalar values in each field. The fields are returned in the same order as specified in `hdfvs('setfields',...)`.
`'seek'`	`pos = hdfvs('seek',vdata_id,record)`	Seeks to a specified record in a vdata.
`'setattr'`	`status = hdfvs('setattr',vdata_id,field_index,name,A)`	Sets the attribute of a vdata field or vdata.
`'setexternalfile'`	`status = hdfvs('setexternalfile',vdata_id,filename,offset)`	Stores vdata information in an external file.
`'getattr'`	`[value,status] = hdfvs('getattr',vdata_id,field_index,attr_index)`	Reads the value of an attribute attached to a vdata or a vdata field. Set `field_index` to `'vdata'` to retrieve an attribute attached to the field itself. Set `field_index` to the numerical index of the field to retrieve an attribute attached to a vdata field.
`'setattr'`	`status = hdfvs('setattr',vdata_id,field_index,name,A)`	Sets the attribute of a vdata field or vdata.`field_index` can be an index number or `'vdata'`.

File Inquiry Functions

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

Value of `funcstr`	Function Syntax	Description
`'find'`	`vdata_ref = hdfvs('find',file_id,vdata_name)`	Searches for a given vdata name in the specified HDF file.
`'findclass'`	`vdata_ref = hdfvs('findclass',file_id,vdata_class)`	Returns the reference number of the first vdata corresponding to the specified vdata class.
`'getid'`	`next_ref = hdfvs('getid',file_id,vdata_ref)`	Returns the identifier of the next vdata in the file.
`'lone'`	`[refs,count] = hdfvs('lone',file_id,maxsize)`	Returns the reference numbers of the vdatas that are not linked into vgroups.

Vdata Inquiry Functions

Vdata inquiry functions provide specific information about a given vdata, including the vdata's name, class, number of fields, number of records, tag and reference pairs, interlace mode, and size.

Value of `funcstr`	Function Syntax	Description
`'fexist'`	`status = hdfvs('fexist',vdata_id,fields)`	Tests for the existence of fields in the specified vdata.
`'inquire'`	`[n,interlace,fields,nbytes,vdata_name,status] = ... hdfvs('inquire',vdata_id)`	Returns information about the specified vdata.
`'elts'`	`count = hdfvs('elts',vdata_id)`	Returns the number of records in the specified vdata.
`'getclass'`	`[class_name,status] = hdfvs('getclass',vdata_id)`	Returns the HDF class of the specified vdata.
`'getfields'`	`[field_names,count] = hdfvs('getfields',vdata_id)`	Returns all field names within the specified vdata.
`'getinterlace'`	`[interlace,status] = hdfvs('getinterlace',vdata_id)`	Retrieves the interlace mode of the specified vdata.
`'getname'`	`[vdata_name,status] = hdfvs('getname',vdata_id)`	Retrieves the name of the specified vdata.
`'getversion'`	`version = hdfvs('getversion',vdata_id)`	Returns the version number of a vdata.
`'sizeof'`	`nbytes = hdfvs('sizeof',vdata_id,fields)`	Returns the fields sizes of the specified vdata.
`'Queryfields'`	`[fields,status] = hdfvs('Queryfields',vdata_id)`	Returns the field names of the specified vdata.
`'Queryname'`	`[name,status] = hdfvs('Queryname',vdata_id)`	Returns the name of the specified vdata.
`'Queryref'`	`ref = hdfvs('Queryref',vdata_id)`	Retrieves the reference number of the specified vdata.
`'Querytag'`	`tag = hdfvs('Querytag',vdata_id)`	Retrieves the tag of the specified vdata.
`'Querycount'`	`[count,status] = hdfvs('Querycount',vdata_id)`	Returns the number of records in the specified vdata.
`'Queryinterlace'`	`[interlace,status] = hdfvs('Queryinterlace',vdata_id)`	Returns the interlace mode of the specified vdata.
`'Queryvsize'`	`vsize = hdfvs('Queryvsize',vdata_id)`	Retrieves the local size in bytes of the specified vdata record.
`'findex'`	`[field_index,status] = hdfvs('findex',vdata_id,fieldname)`	Queries the index of a vdata field given the field name.
`'nattrs'`	`count = hdfvs('nattrs',vdata_id)`	Returns the number of attributes of the specified vdata and the vdata fields contained in it.
`'fnattrs'`	`count = hdfvs('fnattrs',vdata_id,field_index)`	Queries the total number of vdata attributes.
`'findattr'`	`attr_index = hdfvs('findattr',vdata_id,field_index,attr_name)`	Retrieves the index of an attribute given the attribute name.
`'isattr'`	`tf = hdfvs('isattr',vdata_id)`	Determines if the given vdata is an attribute.
`'attrinfo'`	`[name,data_type,count,nbytes,status] = hdfvs('attrinfo',... vdata_id,field_index,attr_index)`	Returns the name, data type, number of values, and the size of the values of the specified attributes of the specified vdata field or vdata.

Output Arguments

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

Version History

Introduced before R2006a