NCDF_BROWSER
This program is designed to make it easier to browse and read the data and metadata in netCDF and HDF files. The user can browse files, and read the data and metadata into main-level IDL variables. New netCDF and HDF files can be opened at any time. The user interacts with the program via a browser window (GUI). This program is a wrapper for the NCDF_DATA object (ncdf_data__define.pro), which must also be downloaded. Note that only HDF files with scientific datasets (SD) can be read currently. There is no support for VDATA objects or other objects sometimes found in HDF files. Also note that when variables are returned from HDF files, they are returned in a calibrated form, if calibration information about the variable is present in the file. Calibration information is presented as an extra variable attribute in the browser. calibratedData = calData.cal * (uncalibratedData - calData.offset)
FANNING SOFTWARE CONSULTING David Fanning, Ph.D. 1645 Sheely Drive Fort Collins, CO 80526 USA Phone: 970-221-0438 E-mail: david@idlcoyote.com Coyote's Guide to IDL Programming: http://www.idlcoyote.com
File I/O
IDL> NCDF_Browser, filename
filename: The name of a netCDF and HDF file to open and browse.
EXTENSION: In general, netCDF and HDF files use *.nc, *.ncf, *.ncdf and *.hdf file extensions to identify themselves as netCDF and HDF files. Some users have their own file extensions. You can use this keyword to identify the file extension you wish to use. If set here, it will be used as the file filter in place of the normal file extensions in DIALOG_PICKFILE. obj = ('NCDF_DATA', file, EXTENSION='*.bin') NO_NEW_FILE: If this keyword is set, then the button that allows a new file to be open on the browser is not created. NO_READ_ON_PARSE: Normally, when a file is opened it is parsed for information. One piece of information is the minimum and maximum values of the variables. This requires actually reading the variables. This can slow things down considerably is the variable is large. Setting this keyword will suppress the reading of the variables during the parsing of the data file, with the result that no minimum or maximum values will be reported. TITLE: Set this keyword to a string that is on the title bar of the browser. XOFFSET: Set this keyword to the X offset in pixels of the top-left corner of the browser. YOFFSET: Set this keyword to the Y offset in pixels of the top-left corner of the browser.
This program is only a (useful) front-end for a more flexible object program of class NCDF_DATA. In this front end, the NCDF_DATA object is created and then destroyed when the GUI is destroyed. The NCDF_DATA object can be used to read netCDF data in a non-interactive way, if you prefer not to use a GUI to interact with the data file.
Written by: David W. Fanning, 03 Feb 2008. Used ideas from many people, including Chris Torrence, Ken Bowman, Liam Gumely, Andrew Slater, and Paul van Delst. Added Extension keyword. DWF. 04 Feb 2008. Added error handling and protection for NCDF variables that have a dimension of length zero. 22 April 2009. DWF. Added NO_READ_ON_PARSE keyword. 22 April 2009. DWF. Now convert NCDF CHAR type variables to strings on output. 22 April 2009. DWF Made the default value of NO_READ_ON_PARSE set to 1. 25 June 2009. DWF. Added NO_NEW_FILE keyword to suppress the Open File button. 3 February 2010. DWF. Added TITLE, XOFFSET, and YOFFSET keywords. 5 February 2010. DWF. Fixed a problem with memory leakage when the input file cannot be read. 1 May 2010. DWF.