The netCDF operators NCO version 3.9.9 are ready.
http://nco.sf.net (Homepage)
http://dust.ess.uci.edu/nco (Homepage "mirror")
This version offers six new significant features:
GSL statistics routines, GSL interpolation routines, netCDF4 chunksize
support (can increase speed of large file reads and writes), netCDF4
string support, record coordinate "re-basing" (climate model
analysts take note!), and one-dimensional offsets in ncap2.
Short explanations of these appear below.
This is the most feature-full release in quite some time.
Work on NCO 4.0.0 is underway. Areas of improvement include
more GSL interpolation and fitting functions, and bilinear
interpolation.
"New stuff" details:
A. ncrcat supports "rebasing", a new feature that relies on UDUnits.
When concatenating multiple input files whose record dimension
uses a units attribute convention like "time-since", and whose
base times vary amongst the files (e.g., "time-since 2001-01-01"
in the first file and "time-since 2002-01-01" in the second),
ncrcat now automatically re-bases the record coordinate values
in the output file so that they all refer to the same base time.
This often produces a monotonically increasing record coordinate
in the output file. Analysis of climate model output in CMIP3-
type collections will be easier as a result.
B. ncap2 supports the GSL (Chapter 20) statistics routines, e.g.,
ncap2 -v -O -s
'defdim("dmn",100);sigma[dmn]=1.0;var1=gsl_ran_gaussian(sigma);var2=gsl_stats_skew(var1);print(var2)'
in.nc out.nc
ncap2 functions added since 3.9.8 are listed below
http://nco.sf.net/nco.html#gsl
C. NCO supports netCDF4 chunking options:
These options can improve performance on large datasets.
Large file users: Send us suggestions on useful chunking patterns!
More advanced chunking patterns will be implemented in NCO 4.0.0.
ncks -O -4 --cnk_plc=all in.nc out.nc
http://nco.sf.net/nco.html#chunking
D. NCO supports the netCDF4 NC_STRING atomic type.
NCO has long-supported the other netCDF4 atomic types.
An "s" trailing double quotes specifies NC_STRING (not NC_CHAR):
ncap2 -4 -O -v -s 'name[lat]={"US"s,"Them"s};' in.nc out.nc
Ragged arrays of strings are finally here! Let's use them.
http://nco.sf.net/nco.html#nco4
E. ncap2 supports GSL (Chapter 27) interpolation routines, e.g.,
gsl_interp_cspline(). Also, missing values handling is improved.
http://nco.sf.net/nco.html#gsl
F. ncap2 LHS hyperslabs of multidimensional variables work with a
single index corresponding to the 1-D array offset, e.g.,
three_dmn_var_dbl(1,1,2)=10.0 is same as three_dmn_var_dbl(14)=10.0
http://nco.sf.net/nco.html#xmp_ncap2
G. UDUnits2 support completed. "time since" handled correctly.
All future units features will utilize UDUnits2.
UDUnits1 support will eventually be deprecated.
H. Operators add an NCO global attribute containing NCO version
I. ncks --secret prints hidden/unsupported options
"Sticky" reminders:
K. Pre-built, up-to-date Debian Sid & Ubuntu Intrepid packages:
http://nco.sf.net#debian
L. Pre-built Fedora and CentOS RPMs:
http://nco.sf.net#rpm
M. Find/add NCO tips and tricks on the NCO Wiki:
http://nco.wiki.sourceforge.net
N. Did you try SWAMP (Script Workflow Analysis for MultiProcessing)?
SWAMP efficiently schedules/executes NCO scripts on remote servers:
http://swamp.googlecode.com
SWAMP can work command-line operator analysis scripts besides NCO.
If you must transfer lots of data from a server to your client
before you analyze it, then SWAMP will likely speed things up.
O. NCO support for netCDF4 features is tracked at
http://nco.sf.net/nco.html#nco4
NCO supports netCDF4 atomic data types, compression, and chunking.
NCO 3.9.9 with was built and tested with HDF5 1.8.3-snap2 and with
netCDF4 4.1-beta1-snapshot2009061712.
NCO may not build with earlier, but should build with later, netCDF4
releases.
This is particularly true with NCO 3.9.9 which takes advantage of
an internal change to the netCDF API for nc_def_var_chunking().
export NETCDF4_ROOT=/usr/local/netcdf4 # Set netCDF4 location
cd ~/nco;./configure --enable-netcdf4 # Configure mechanism -or-
cd ~/nco/bld;./make NETCDF4=Y allinone # Old Makefile mechanism
P. Have you seen the NCO logo candidates by Tony Freeman and Rich Signell?
http://nco.sf.net/logo_pch.png
http://nco.sf.net/logo_cog.png
Tell us what you think...
Enjoy,
Charlie
GSL functions added to ncap2 in 3.9.9:
ncap2 -f | grep gsl_interp
ncap2 -f | grep gsl_stats
gsl_interp_akima()
gsl_interp_akima_periodic()
gsl_interp_cspline()
gsl_interp_cspline_periodic()
gsl_interp_linear()
gsl_interp_polynomial()
gsl_stats_absdev()
gsl_stats_absdev_m()
gsl_stats_correlation()
gsl_stats_covariance()
gsl_stats_kurtosis()
gsl_stats_lag1_autocorrelation()
gsl_stats_lag1_autocorrelation_m()
gsl_stats_max()
gsl_stats_max_index()
gsl_stats_mean()
gsl_stats_median_from_sorted_data()
gsl_stats_min()
gsl_stats_min_index()
gsl_stats_pvariance()
gsl_stats_quantile_from_sorted_data()
gsl_stats_sd()
gsl_stats_sd_m()
gsl_stats_sd_with_fixed_mean()
gsl_stats_skew()
gsl_stats_ttest()
gsl_stats_variance()
gsl_stats_variance_m()
gsl_stats_variance_with_fixed_mean()
gsl_stats_wabsdev()
gsl_stats_wabsdev_m()
gsl_stats_wkurtosis()
gsl_stats_wkurtosis_m_sd()
gsl_stats_wmean()
gsl_stats_wsd()
gsl_stats_wsd_m()
gsl_stats_wsd_with_fixed_mean()
gsl_stats_wskew()
gsl_stats_wskew_m_sd()
gsl_stats_wvariance()
gsl_stats_wvariance_m()
gsl_stats_wvariance_with_fixed_mean()
--
Charlie Zender, Department of Earth System Science
University of California, Irvine (949) 231-7002 :)
