Cdo.{rb,py} - Use Ruby/Python to access the power of CDO¶ ↑

This package contains the module Cdo, which implements a ruby/python style access to the Climate Data operators CDO. CDO is a command line tool for processing gridded data. Its main focus if climate data, but it can by used for other purposes to. It accepts input formats GRIB1, GRIB2, NetCDF and several Fortran binary formats.

Installation¶ ↑

Ruby Installation¶ ↑

Download and install cdo.rb via rubygems:

gem install cdo

Python Installation¶ ↑

Download and install cdo.py via pypi:

pip install cdo

Requirements¶ ↑

Cdo.{rb,py} requires a working CDO binary, but has not special requirement to ruby or python. For returning multi-dimensional arrays (numpy for python, narray for ruby) addtional netcdf-io modules are needed. These are scipy/netcdf4 for python and ruby-netcdf for ruby.

Usage¶ ↑

Run operators¶ ↑

The Ruby module can be used directly after loading it. For python an instance has to be created first

cdo = Cdo()

File information

Cdo.infov(:input => ifile)       (ruby)
Cdo.showlevels(:input => ifile)

cdo.infov(input=ifile)         (python)
cdo.showlevels(input=ifile)

Operators with user defined regular output files

Cdo.timmin(:input => ifile ,:output => ofile) (ruby)
cdo.timmin(input = ifile,output = ofile)    (python)

Use temporary output files

tminFile = Cdo.timmin(:input => ifile) (ruby)
tminFile = cdo.timmin(input = ifile) (python)

Operators with options

Cdo.remap([gridfile,weightfile],:input => ifile, :output => ofile) (ruby)
cdo.remap([gridfile,weightfile],input => ifile, output => ofile) (python)

Set global CDO options

Cdo.copy(:input => ifile, :output => ofile,:options => "-f nc4") (ruby)
cdo.copy(input = ifile, output = ofile,options = "-f nc4")     (python)

Set environment variables

Cdo.splitname(:input => ifile.join(' '), :output => 'splitTag',:env {'CDO_FILE_SUFFIX' => '.nc'}) (ruby)
or Cdo.env = {'CDO_FILE_SUFFIX' => '.nc'}
cdo.splitname(input = ' '.join(ifiles) ,  output =  'splitTag', env={"CDO_FILE_SUFFIX": ".nc"})   (python)
or Cdo.env = {'CDO_FILE_SUFFIX': '.nc'}

Return multi-dimension arrrays

temperatures = Cdo.fldmin(:input => ifile,:returnArray => true).var('T').get   (rb, version < 1.2.0)
temperatures = cdo.fldmin(input = ifile,returnArray = True).variables['T'][:] (py, version < 1.2.0)
temperatures = Cdo.fldmin(:input => ifile,:returnCdf => true).var('T').get    (rb, version >= 1.2.0)
temperatures = cdo.fldmin(input = ifile,returnCdf = True).variables['T'][:]   (py, version >= 1.2.0)*
temperatures = Cdo.fldmin(:input => ifile,:returnArray => 'T')                (rb, version >= 1.2.0)
temperatures = cdo.fldmin(input = ifile,returnArray = 'T')                   (py, version >= 1.2.0)

*) If you use scipy >= 0.14 as netcdf backend, you have use following code instead to avoid possible segmentation faults:

cdf = cdo.fldmin(input = ifile,returnCdf = True)
temperatures = cdf.variables['T'][:]

More examples can be found in test/cdo-examples.rb and on the homepage: code.zmaw.de/projects/cdo/wiki/Cdo%7Brbpy%7D

Tempfile helpers¶ ↑

Cdo.{rb,py} includes a simple tempfile wrapper, which make live easier, when write your own scripts

Support, Issues, Bugs, …¶ ↑

Please use the forum or ticket system of CDOs official web page: code.zmaw.de/projects/cdo

Changelog¶ ↑

- return arrays/lists of output files, which are created by split* operators
  suggestion from Karl-Hermann Wieners

1.3 (upcomming)

- require ruby-2.*
- support object interface in the ruby version (easy setup of options during initializaion, thread safety)
- allow environment variables set with external JSON file

1.2.7

- Added class interface for ruby version 2.x

1.2.6

- bugfix for autocompletion in interactive usage [python-only]

1.2.5

- bugfix for environment handling (Thanks philipp) [python-only]
- add logging [ruby-only]

1.2.4

- support python3: Thanks to @jhamman
- bugfix for scipy: Thanks to @martinclaus
- docu fixes: Thanks to @guziy
- allow environment setting via call and object construction (see test_env in test_cdo.py)

1.2.3

- bugfix release: adjust library/feature check to latest cdo-1.6.2  release

1.2.2

- allow arrays in additions to strings for input argument
- add methods for checking the IO libraries of CDO and their versions
- optionally return None on error (suggestion from Alex Loew, python only)

1.2.1:

- new return option: Masked Arrays
  if the new keyword returnMaArray is given, its value is taken as variable
  name and a masked array wrt to its FillValues is returned
  contribution for python by Alex Loew
- error handling: return stderr in case of non-zero return value + raise exception
  contribution for python from Estanislao Gonzalez
- autocompletion and built-in documentation through help() for interactive use
  contribution from Estanislao Gonzalez [python]
- Added help operator for displaying help interactively [ruby]

1.2.0: API change:

- Ruby now uses the same keys like the python interface, i.e. :input and :output
  instead of :in and :out
- :returnArray will accept a variable name, for which the multidimesional
  array is returned

1.1.0: API change:

- new option :returnCdf : will return the netcdf file handle, which was formerly
  done via :returnArray
- new options :force : if set to true the cdo call will be run even if the given
  output file is presen, default: false

License¶ ↑

Cdo.{rb,py} makes use of the GPLv2 License, see COPYING

Other stuff¶ ↑

Author: Ralf Mueller <stark.dreamdetective@gmail.com>
Requires: CDO version 1.5.x or newer
License: Copyright 2011-2015 by Ralf Mueller Released under GPLv2 license. See the COPYING file included in the distribution.

illing2005 / cdo-bindings