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hdfinfo

Return information about an HDF or HDF-EOS file

Syntax

Description

S = hdfinfo(filename) returns a structure S whose fields contain information about the contents of an HDF or HDF-EOS file. filename is a string that specifies the name of the HDF file.

S = hdfinfo(filename,mode) reads the file as an HDF file, if mode is 'hdf', or as an HDF-EOS file, if mode is 'eos'. If mode is 'eos', only HDF-EOS data objects are queried. To retrieve information on the entire contents of a file containing both HDF and HDF-EOS objects, mode must be 'hdf'.

The set of fields in the returned structure S depends on the individual file. Fields that can be present in the S structure are shown in the following table.

HDF Object Fields
Mode
Field Name
Description
Return Type
HDF
Attributes
Attributes of the data set
Structure array
Description
Annotation description
Cell array
Filename
Name of the file
String
Label
Annotation label
Cell array
Raster8
Description of 8-bit raster images
Structure array
Raster24
Description of 24-bit raster images
Structure array
SDS
Description of scientific data sets
Structure array
Vdata
Description of Vdata sets
Structure array
Vgroup
Description of Vgroups
Structure array
EOS
Filename
Name of the file
String
Grid
Grid data
Structure array
Point
Point data
Structure array
Swath
Swath data
Structure array

Those fields in the table above that contain structure arrays are further described in the tables shown below.

Fields Common to Returned Structure Arrays

Structure arrays returned by hdfinfo contain some common fields. These are shown in the table below. Not all structure arrays will contain all of these fields.

Common Fields
Field Name
Description
Data Type
Attributes
Data set attributes. Contains fields Name and Value.
Structure array
Description
Annotation description
Cell array
Filename
Name of the file
String
Label
Annotation label
Cell array
Name
Name of the data set
String
Rank
Number of dimensions of the data set
Double
Ref
Data set reference number
Double
Type
Type of HDF or HDF-EOS object
String

Fields Specific to Certain Structures

Structure arrays returned by hdfinfo also contain fields that are unique to each structure. These are shown in the tables below.

Fields of the Attribute Structure
Field Name
Description
Data Type
Name
Attribute name
String
Value
Attribute value or description
Numeric or string


Fields of the Raster8 and Raster24 Structures
Field Name
Description
Data Type
HasPalette
1 (true) if the image has an associated palette, otherwise 0 (false) (8-bit only)
Logical
Height
Height of the image, in pixels
Number
Interlace
Interlace mode of the image (24-bit only)
String
Name
Name of the image
String
Width
Width of the image, in pixels
Number


Fields of the SDS Structure
Field Name
Description
Data Type
DataType
Data precision
String
Dims
Dimensions of the data set. Contains fields Name, DataType, Size, Scale, and Attributes. Scale is an array of numbers to place along the dimension and demarcate intervals in the data set.
Structure array
Index
Index of the SDS
Number


Fields of the Vdata Structure
Field Name
Description
Data Type
DataAttributes
Attributes of the entire data set. Contains fields Name and Value.
Structure array
Class
Class name of the data set
String
Fields
Fields of the Vdata. Contains fields Name and Attributes.
Structure array
NumRecords
Number of data set records
Double
IsAttribute
1 (true) if Vdata is an attribute, otherwise 0 (false)
Logical


Fields of the Vgroup Structure
Field Name
Description
Data Type
Class
Class name of the data set
String
Raster8
Description of the 8-bit raster image
Structure array
Raster24
Description of the 24-bit raster image
Structure array
SDS
Description of the Scientific Data sets
Structure array
Tag
Tag of this Vgroup
Number
Vdata
Description of the Vdata sets
Structure array
Vgroup
Description of the Vgroups
Structure array


Fields of the Grid Structure
Field Name
Description
Data Type
Columns
Number of columns in the grid
Number
DataFields
Description of the data fields in each Grid field of the grid. Contains fields Name, Rank, Dims, NumberType, FillValue, and TileDims.
Structure array
LowerRight
Lower right corner location, in meters
Number
Origin Code
Origin code for the grid
Number
PixRegCode
Pixel registration code
Number
Projection
Projection code, zone code, sphere code, and projection parameters of the grid. Contains fields ProjCode, ZoneCode, SphereCode, and ProjParam.
Structure
Rows
Number of rows in the grid
Number
UpperLeft
Upper left corner location, in meters
Number


Fields of the Point Structure
Field Name
Description
Data Type
Level
Description of each level of the point. Contains fields Name, NumRecords, FieldNames, DataType, and Index.
Structure


Fields of the Swath Structure
Field Name
Description
Data Type
DataFields
Data fields in the swath. Contains fields Name, Rank, Dims, NumberType, and FillValue.
Structure array
GeolocationFields
Geolocation fields in the swath. Contains fields Name, Rank, Dims, NumberType, and FillValue.
Structure array
IdxMapInfo
Relationship between indexed elements of the geolocation mapping. Contains fields Map and Size.
Structure
MapInfo
Relationship between data and geolocation fields. Contains fields Map, Offset, and Increment.
Structure

Examples

To retrieve information about the file example.hdf,

And to retrieve information from this about the scientific data set in example.hdf,

See Also

hdfread, hdf


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