Hi,
This note announces Harvey Davies' FAN software, a new package for
manipulating netCDF data. FAN (File Array Notation) is an array-oriented
notation for identifying data items in files for the purpose of extraction
or modification. NetCDF is the only file format currently supported by the
FAN utilities, but there may eventually be FAN interfaces to other formats.
The three utility programs (nc2text, text2nc, and ncrob) in the initial
release can reduce the need for programming, because the utilities can be
called from shell scripts and the UNIX command line.
The nc2text utility prints selected data from netCDF arrays. The standard
utility ncdump can also print data from netCDF arrays, but only entire
arrays and only together with metadata in CDL form.
The text2nc utility can be used to read small volumes (say up to a few
thousand lines) of ASCII data and copy it into netCDF arrays. FAN can be
used to specify the elements to be modified. It is also possible to use
text2nc to create, modify and delete attributes.
The nc2text and text2nc programs may be used instead of ncdump and ncgen for
many kinds of netCDF data extraction and modification. For example,
transforming data between netCDF and spreadsheet formats is easier with a
shell script that uses nc2text/text2nc than ncdump/ncgen.
The ncrob utility reads data from one or more netCDF arrays, performs some
process on the data and then writes the result to a netCDF array. The
letters `rob' in `ncrob' stand for Reduce Or Broadcast. Reduce means to
produce an array (e.g., sum, mean, maximum) with fewer dimensions than the
original. Broadcast means to (repeatedly if necessary) copy an array to
another with at least the same number of dimensions. An example would be
copying the same vector to each row of a matrix. It is possible to process
large volumes of data (e.g., 100 MB) using ncrob.
The FAN utilities and supporting library are available in source form via
anonymous FTP from
ftp://ftp.unidata.ucar.edu/pub/netcdf/contrib/fan.tar.Z
A longer document describing the FAN notation and utilities--including many
small but useful examples--is available in TeX and PostScript form with the
package. This document is also available to WWW browsers via the following
URL:
http://www.unidata.ucar.edu/packages/netcdf/fan_utils.html
FAN has been built and tested successfully on the following platforms:
AIX-4.1
HPUX-9.05
IRIX-5.3
IRIX64-6.0.1
OSF1-3.0
SunOS-4.1.4
SunOS-5.4
Ultrix-4.4
Besides netCDF, FAN also requires the Unidata UDUNITS package, available from
ftp://ftp.unidata.ucar.edu/pub/udunits/
Steve Emmerson of Unidata adapted Davies' FAN package to use the same system
for building and porting the package that we use for netCDF and other
Unidata packages. Russ Rew created the HTML version of the FAN Utilities
document and did some of the testing.
For support with the FAN package, contact Harvey Davies (hld@xxxxxxxxxxxx).
The reason we (rather than Harvey Davies) are sending this announcement to
the netcdfgroup mailing list, is that Davies is currently traveling from
CSIRO in Australia to Atlanta, Georgia, to talk about FAN and netCDF at the
"Second Workshop on Database Issues for Data Visualization" and the
subsequent "IEEE Visualization '95" conference.
We're also very pleased to announce that Davies has accepted a seven-month
scientific-visitor position with UCAR/Unidata starting in January 1996 to
work on netCDF development.
Russ Rew russ@xxxxxxxxxxxxxxxx
Steve Emmerson steve@xxxxxxxxxxxxxxxx
