HDF(3) Library Functions Manual HDF(3)
NAME
hdf - Hierarchical Data Format library
SYNOPSIS
-lmfhdf -ldf -ljpeg -lz [ -lsz ]
/usr/lib/libmfhdf.a /usr/lib/libdf.a /usr/lib/libjpeg.a /usr/lib/libz.a
/usr/lib/libsz.a
DESCRIPTION
HDF is a multi-object file format that facilitates the transfer of var-
ious types of scientific data between machines and operating systems.
See http://www.hdfgroup.org/release4/platforms.html for a list of plat-
forms currently supported.
HDF allows self-definitions of data content and easy extensibility for
future enhancements or compatibility with other standard formats. HDF
includes Fortran and C calling interfaces, and utilities for manipulat-
ing, viewing, and analyzing data in HDF files. The HDF library contains
interfaces for storing and retrieving compressed or uncompressed 8-bit
and 24-bit raster images with palettes, n-Dimensional scientific
datasets and binary tables. An interface is also included that allows
arbitrary grouping of other HDF objects.
HDF Raster Images
HDF supports the storing of both 8-bit and 24-bit raster images. Be-
side storing information about the dimensions and palette of a raster
image, HDF supports raster image compression. In previous versions of
HDF (DF interfaces,) Run-length encoding and Imcomp compression were
both supported. The currently supported compression methods include
simple RLE, N-bit, Skipping huffman, Gzip, Szip, and JPEG. Although no
longer support Imcomp compression, the library can read images with Im-
comp compression.
HDF Scientific Data Sets
Scientific Data Sets (SDSs) are useful for storing n-Dimensional grid-
ded data. The actual data in the dataset can be of any of the "stan-
dard" number types: 8, 16 and 32bit signed and unsigned integers and 32
and 64bit floating point values. In addition, a certain amount of
meta-data can be stored with an SDS including:
o The coordinate system to use when interpreting or displaying the data.
o Scales to be used for each dimension.
o Labels for each dimension and the dataset as a whole.
o Units for each dimension and the data.
o The valid max and min values for the data.
o Calibration information for the data.
o Fill or missing value information.
o Ability of having more than one file open at a time.
o A more general framework for meta-data within the SDS data-model
(allowing 'name = value' style meta-data.)
o Support for an "unlimited dimension" in the SDS data-model, making
it possible to append planes to an array along one dimension.
HDF Annotations
Any object in an HDF file can have annotations associated with it.
There are a number of types of annotations:
o Labels are assumed to be short strings giving the "name" of a
data object.
o Descriptions are longer text segments that are useful for giving
more indepth information about a data object
o File annotations are assumed to apply to all of the objects in a
single file.
HDF Vset Interfaces
The Vset module provides interfaces to two basic HDF building blocks.
Vgroups are generic grouping elements allowing a user to associate re-
lated objects within an HDF file. As Vgroups can contain other
Vgroups, it is possible to build a hierarchical file. Vdatas are data
structures made up of fields and records. Data is organized into
"fields" within each Vdata. Each field is identified by a unique
"fieldname". The type of each field may be any of the basic number
types that HDF supports. Fields of different types may exist within
the same Vdata.
By combining Vdatas in Vgroups it is possible to represent higher level
data constructs: mesh data, multi-variate datasets, sparse matrices,
finite-element data, spreadsheets, splines, non-Cartesian coordinate
data, etc.
HDF and netCDF
Starting with HDF version 3.3, netCDF v.2.3.2 of Unidata is supported
with the SD multifile interface. SD and netCDF interfaces can read both
netCDF files and multi-dimensional arrays (SDS) stored in the HDF4
files transparently. For more information, see Chapter 3, "Scientific
Data Sets", of the HDF User's Guide.
To disable netCDF interfaces in the HDF library, configure the library
using --disable-netcdf flag and rebuild it.
EXAMPLES
All HDF routines require the header "hdf.h" to be included in the C
source file, unless if the SD routines are used, then the header
"mfhdf.h" should be included instead.
Fortran programs should use "dffunc.inc" for all interfaces, "mf-
func.inc" for the SD interfaces, and "hdf.inc" for non-SD interfaces.
To compile a program that makes HDF calls on most Unix platforms.
(FORTRAN):
{HDFLIBDIR}/bin/h4fc myprog.f
(C):
{HDFLIBDIR}/bin/h4cc myprog.c
DOCUMENTATION
The HDF web site is located at http://www.hdfgroup.org/.
For the vast majority of users, the "HDF User's Guide" and "HDF Refer-
ence Manual" should be sufficient.
These documents can be viewed or downloaded at
http://www.hdfgroup.org/products/hdf4/.
VENDOR
The HDF Group
1800 South Oak Street, Suite 203
Champaign, IL 61820
USA
www.hdfgroup.org
VERSION
4.2.15
LICENSE & SOURCE AVAILABILITY
Copyright by The HDF Group.
Copyright by the Board of Trustees of the University of Illinois.
All rights reserved.
This file is part of HDF. The full HDF copyright notice, including
terms governing use, modification, and redistribution, is contained in
the COPYING file, which can be found at the root of the source code
distribution tree, or in https://support.hdfgroup.org/ftp/HDF/re-
leases/.
If you do not have access to either file, you may request a copy from
help@hdfgroup.org.
CONTACT & HELP
The HDF Group
Email: help@hdfgroup.org
FILES
/usr/lib/{libmfhdf,libdf,libjpeg,libz,libsz}.{a,so}
hdf libraries
/usr/bin Location of most hdf utilities
/usr/include/hdf Location of include file hdf.h, mfhdf.h,
and others
THG HDF 4.2.15 November 2019 HDF(3)
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