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.

Why the .… should I use this???

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. Both python2 and python3 are fully supported. The class interface of the ruby version requires at least ruby-2.x, the module interface (available in ‘cdo_lib’) works with ruby-1.9.x, too. 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 and the ruby class interface an instance has to be created first

cdo = Cdo.new
cdo = Cdo()

Please check the documentation for constructor paramaters

• File information

  Cdo.infov(:input => ifile)       (ruby, module interface)
  Cdo.showlevels(:input => ifile)
  
  cdo.infov(input: ifile)       (ruby-2.*, class interface)
  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) (ruby-2.*, class interface
  cdo.timmin(input = ifile,output = ofile)    (python)

• Use temporary output files

  tminFile = Cdo.timmin(:input => ifile) (ruby)
  tminFile = cdo.timmin(input: ifile) (ruby-2.*, class interface)
  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) (ruby-2.x, class interface)
  cdo.remap([gridfile,weightfile],input => ifile, output => ofile) (python)

• logging

  cdo = Cdo.new(logging: true, logFile: 'cdo_commands.log') [ruby-2.x]
  cdo = Cdo(logging=True, logFile='cdo_commands.log')       [python]
  

• Set global CDO options

  Cdo.copy(:input => ifile, :output => ofile,:options => "-f nc4") (ruby)
  cdo.copy(input:  ifile, output:  ofile,options:  "-f nc4")     (ruby-2.x, class interface)
  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'}
  xdo.splitname(input:    ifile.join(' '), output:    'splitTag',env: {'CDO_FILE_SUFFIX' => '.nc'}) (ruby-2.x, class interface)
  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¶ ↑

• next:

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

• 1.3.2 [2016-10-24]

  - improvened stdout/stderr handling, thx to jvegasbsc

• 1.3.1

  - fix environment handling per call (ruby version)

• 1.3.0

  - require ruby-2.*
  - support for upcomming CDO release 1.7.1
  - improve loggin for ruby
  - introduce logging for python
  - unicode bugfix - thanks to Sebastian Illing (illing2005) [python-only]

• 1.2.7

  - Added class interface for ruby version 2.x, mainly for thread safety

• 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

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Other stuff¶ ↑

Author

Ralf Mueller <[email protected]>

Requires

CDO version 1.5.x or newer

License

Copyright 2011-2017 by Ralf Mueller Released under GPLv2 license. See the COPYING file included in the distribution.