CDF User's Guide Version 3.4, February 28, 2012 Space Physics Data Facility NASA / Goddard Space Flight Center Copyright © 2012 NASA/GSFC Space Physics Data Facility NASA/Goddard Space Flight Center Greenbelt, Maryland 20771 (U.S.A.) This software may be copied or redistributed as long as it is not sold for profit, but it can be incorporated into any other substantive product with or without modifications for profit or non-profit. If the software is modified, it must include the following notices: - The software is not the original (for protection of the original author’s reputations from any problems introduced by others) - Change history (e.g. date, functionality, etc.) This copyright notice must be reproduced on each copy made. This software is provided as is without any express or implied warranties whatsoever. Internet: [email protected] Permission is granted to make and distribute verbatim copies of this document provided this copyright and permission notice are preserved on all copies. Contents 1 Primer.....................................................................................................................................5 1.1 Introduction................................................................................................................................................................ 5 1.2 Why use CDF?........................................................................................................................................................... 5 1.3 Conceptual Organization........................................................................................................................................... 5 1.4 Features of the CDF Library ..................................................................................................................................... 6 1.4.1 File Format Options .......................................................................................................................................... 7 1.4.2 Data Encoding Options................................................................................................................................... 12 1.4.3 Compression.................................................................................................................................................... 12 1.4.4 Sparseness........................................................................................................................................................ 12 1.4.5 Variable Data Access Options........................................................................................................................ 12 1.5 Organizing Your Data in a CDF ............................................................................................................................. 13 1.5.1 Variables.......................................................................................................................................................... 13 1.6 Attributes ................................................................................................................................................................. 16 1.7 CDF Toolkit............................................................................................................................................................. 17 1.8 Library Interface Routines ...................................................................................................................................... 18 1.8.1 Standard Interface ........................................................................................................................................... 18 1.8.2 Internal Interface ............................................................................................................................................. 19 1.9 CDF Java Interface.................................................................................................................................................. 19 1.10 How to create a CDF........................................................................................................................................... 19 1.10.1 Sample C, Fortran, Java, Perl and C# Programs............................................................................................ 19 1.10.2 Creating a CDF with CDFEdit ....................................................................................................................... 19 1.10.3 Creating a CDF with SkeletonTable............................................................................................................... 19 2 Concepts ...............................................................................................................................23 2.1 CDF Library............................................................................................................................................................. 23 2.1.1 Interfaces ......................................................................................................................................................... 23 2.1.2 CDF Modes ..................................................................................................................................................... 24 2.1.3 Limits............................................................................................................................................................... 26 2.1.4 Scratch Files .................................................................................................................................................... 26 2.1.5 Caching Scheme.............................................................................................................................................. 26 2.2 CDFs ........................................................................................................................................................................ 28 2.2.1 Accessing......................................................................................................................................................... 28 2.2.2 Creating ........................................................................................................................................................... 28 2.2.3 Opening ........................................................................................................................................................... 28 2.2.4 Closing............................................................................................................................................................. 28 2.2.5 Deleting ........................................................................................................................................................... 29 2.2.6 Naming ............................................................................................................................................................ 29 2.2.7 Format.............................................................................................................................................................. 29 2.2.8 Encoding.......................................................................................................................................................... 31 2.2.9 Decoding.......................................................................................................................................................... 33 2.2.10 Compression.................................................................................................................................................... 35 2.2.11 Limits............................................................................................................................................................... 35 2.3 Variables .................................................................................................................................................................. 35 2.3.1 Types................................................................................................................................................................ 36 2.3.2 Accessing......................................................................................................................................................... 36 2.3.3 Opening ........................................................................................................................................................... 36 2.3.4 Closing............................................................................................................................................................. 36 2.3.5 Naming ............................................................................................................................................................ 37 2.3.6 Numbering....................................................................................................................................................... 37 2.3.7 Deleting ........................................................................................................................................................... 37 2.3.8 Dimensionality ................................................................................................................................................ 37 2.3.9 Data Specification ..........................................................................................................................................