cma


Namecma JSON
Version 4.3.0 PyPI version JSON
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SummaryCMA-ES, Covariance Matrix Adaptation Evolution Strategy for non-linear numerical optimization in Python
upload_time2025-07-24 11:32:18
maintainerNone
docs_urlNone
authorYouhei Akimoto, Petr Baudis
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licenseNone
keywords optimization cma-es cmaes
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            CMA-ES Covariance Matrix Adaptation Evolution Strategy
======================================================

A stochastic numerical optimization algorithm for difficult (non-convex,
ill-conditioned, multi-modal, rugged, noisy) optimization problems in
continuous search spaces, implemented in Python.

Typical domain of application are unconstrained or bound-constrained
objective functions with:

* search space dimension between, say, 5 and (a few) 100,
* no gradients available,
* at least, say, 100 times dimension function evaluations needed to
  get satisfactory solutions,
* non-separable, ill-conditioned, or rugged/multi-modal landscapes.

More recently nonlinear constraints handling is available too.
The CMA-ES is quite reliable, however for small budgets (fewer function
evaluations than, say, 100 times dimension) or in very small dimensions
faster methods are available.

The ``pycma`` module provides two independent implementations of the 
CMA-ES algorithm in the classes ``cma.CMAEvolutionStrategy`` and 
``cma.purecma.CMAES``. 

Installation
------------
In the terminal command line type::

      python -m pip install cma

The package will be downloaded and installed automatically. To **upgrade**
an existing installation, '``pip``' must be replaced by '``pip -U``'. For
the documentation of ``pip``, `see here`_.

.. _`see here`: http://www.pip-installer.org

Alternatively, download and unpack the ``cma-...tar.gz``. The folder
``cma`` from the ``tar`` archive can used without any installation
(for ``import`` to find it, it must be in the current folder or the Python
search paths) or can be installed by ``pip install -e .``.

Usage Example
-------------
In a Python shell::

    >>> import cma
    >>> help(cma)
        <output omitted>
    >>> es = cma.CMAEvolutionStrategy(8 * [0], 0.5)
    (5_w,10)-aCMA-ES (mu_w=3.2,w_1=45%) in dimension 8 (seed=468976, Tue May  6 19:14:06 2014)
    >>> help(es)  # the same as help(cma.CMAEvolutionStrategy)
        <output omitted>
    >>> es.optimize(cma.ff.rosen)
    Iterat #Fevals   function value    axis ratio  sigma  minstd maxstd min:sec
        1      10 1.042661803766204e+02 1.0e+00 4.50e-01  4e-01  5e-01 0:0.0
        2      20 7.322331708590002e+01 1.2e+00 3.89e-01  4e-01  4e-01 0:0.0
        3      30 6.048150359372417e+01 1.2e+00 3.47e-01  3e-01  3e-01 0:0.0
      100    1000 3.165939452385367e+00 1.1e+01 7.08e-02  2e-02  7e-02 0:0.2
      200    2000 4.157333035296804e-01 1.9e+01 8.10e-02  9e-03  5e-02 0:0.4
      300    3000 2.413696640005903e-04 4.3e+01 9.57e-03  3e-04  7e-03 0:0.5
      400    4000 1.271582136805314e-11 7.6e+01 9.70e-06  8e-08  3e-06 0:0.7
      439    4390 1.062554035878040e-14 9.4e+01 5.31e-07  3e-09  8e-08 0:0.8
    >>> es.result_pretty()  # pretty print result
    termination on tolfun=1e-11
    final/bestever f-value = 3.729752e-15 3.729752e-15
    mean solution: [ 1.          1.          1.          1.          0.99999999  0.99999998
      0.99999995  0.99999991]
    std deviation: [  2.84303359e-09   2.74700402e-09   3.28154576e-09   5.92961588e-09
       1.07700123e-08   2.12590385e-08   4.09374304e-08   8.16649754e-08]

optimizes the 8-dimensional Rosenbrock function with initial solution all
zeros and initial ``sigma = 0.5``.

Pretty much the same can be achieved a little less "elaborate" with::

    >>> import cma
    >>> xopt, es = cma.fmin2(cma.ff.rosen, 8 * [0], 0.5)
        <output omitted>

And a little more elaborate exposing the **ask-and-tell interface**::

    >>> import cma
    >>> es = cma.CMAEvolutionStrategy(12 * [0], 0.5)
    >>> while not es.stop():
    ...     solutions = es.ask()
    ...     es.tell(solutions, [cma.ff.rosen(x) for x in solutions])
    ...     es.logger.add()  # write data to disc to be plotted
    ...     es.disp()
        <output omitted>
    >>> es.result_pretty()
        <output omitted>
    >>> cma.plot()  # shortcut for es.logger.plot()

.. figure:: http://www.cmap.polytechnique.fr/~nikolaus.hansen/rosen12.png
    :alt: CMA-ES on Rosenbrock function in dimension 8
    :target: https://cma-es.github.io/cmaes_sourcecode_page.html#example
    :align: center 
   
    A single run on the 12-dimensional Rosenbrock function. 


The ``CMAOptions`` class manages options for ``CMAEvolutionStrategy``,
e.g. verbosity options can be found like::

    >>> import cma
    >>> cma.s.pprint(cma.CMAOptions('erb'))
    {'verb_log': '1  #v verbosity: write data to files every verb_log iteration, writing can be time critical on fast to evaluate functions'
     'verbose': '1  #v verbosity e.v. of initial/final message, -1 is very quiet, not yet implemented'
     'verb_plot': '0  #v in fmin(): plot() is called every verb_plot iteration'
     'verb_disp': '100  #v verbosity: display console output every verb_disp iteration'
     'verb_filenameprefix': 'outcmaes  # output filenames prefix'
     'verb_append': '0  # initial evaluation counter, if append, do not overwrite output files'
     'verb_time': 'True  #v output timings on console'}

Options are passed like::

    >>> import cma
    >>> es = cma.CMAEvolutionStrategy(8 * [0], 0.5,
                                      {'verb_disp': 1}) # display each iteration


Documentations
--------------
The full package API documentation:

* `version 3+`_ (recent)
* `version 1.x`_

.. _`version 3+`: https://cma-es.github.io/apidocs-pycma/
.. _`version 1.x`: http://www.cmap.polytechnique.fr/~nikolaus.hansen/html-pythoncma/

See also

* `Github page hosting this code`_ and its `FAQ`_ (under development)
* `General CMA-ES source code page`_ with practical hints
* `CMA-ES on Wikipedia`_

.. _`Github page hosting this code`: https://github.com/CMA-ES/pycma
.. _`FAQ`: https://github.com/CMA-ES/pycma/issues?q=is:issue+label:FAQ
.. _`General CMA-ES source code page`: https://cma-es.github.io/cmaes_sourcecode_page.html
.. _`CMA-ES on Wikipedia`: http://en.wikipedia.org/wiki/CMA-ES

Dependencies
------------

* required (unless for `cma.purecma`): ``numpy`` -- array processing for numbers, strings, records, and objects
* optional (highly recommended): ``matplotlib`` -- Python plotting package (includes ``pylab``)

Use ``pip install numpy`` etc. for installation. The `cma.purecma` submodule can be used without any dependencies installed.

License: BSD-3-Clause

            

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    "description": "CMA-ES Covariance Matrix Adaptation Evolution Strategy\n======================================================\n\nA stochastic numerical optimization algorithm for difficult (non-convex,\nill-conditioned, multi-modal, rugged, noisy) optimization problems in\ncontinuous search spaces, implemented in Python.\n\nTypical domain of application are unconstrained or bound-constrained\nobjective functions with:\n\n* search space dimension between, say, 5 and (a few) 100,\n* no gradients available,\n* at least, say, 100 times dimension function evaluations needed to\n  get satisfactory solutions,\n* non-separable, ill-conditioned, or rugged/multi-modal landscapes.\n\nMore recently nonlinear constraints handling is available too.\nThe CMA-ES is quite reliable, however for small budgets (fewer function\nevaluations than, say, 100 times dimension) or in very small dimensions\nfaster methods are available.\n\nThe ``pycma`` module provides two independent implementations of the \nCMA-ES algorithm in the classes ``cma.CMAEvolutionStrategy`` and \n``cma.purecma.CMAES``. \n\nInstallation\n------------\nIn the terminal command line type::\n\n      python -m pip install cma\n\nThe package will be downloaded and installed automatically. 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The folder\n``cma`` from the ``tar`` archive can used without any installation\n(for ``import`` to find it, it must be in the current folder or the Python\nsearch paths) or can be installed by ``pip install -e .``.\n\nUsage Example\n-------------\nIn a Python shell::\n\n    >>> import cma\n    >>> help(cma)\n        <output omitted>\n    >>> es = cma.CMAEvolutionStrategy(8 * [0], 0.5)\n    (5_w,10)-aCMA-ES (mu_w=3.2,w_1=45%) in dimension 8 (seed=468976, Tue May  6 19:14:06 2014)\n    >>> help(es)  # the same as help(cma.CMAEvolutionStrategy)\n        <output omitted>\n    >>> es.optimize(cma.ff.rosen)\n    Iterat #Fevals   function value    axis ratio  sigma  minstd maxstd min:sec\n        1      10 1.042661803766204e+02 1.0e+00 4.50e-01  4e-01  5e-01 0:0.0\n        2      20 7.322331708590002e+01 1.2e+00 3.89e-01  4e-01  4e-01 0:0.0\n        3      30 6.048150359372417e+01 1.2e+00 3.47e-01  3e-01  3e-01 0:0.0\n      100    1000 3.165939452385367e+00 1.1e+01 7.08e-02  2e-02  7e-02 0:0.2\n      200    2000 4.157333035296804e-01 1.9e+01 8.10e-02  9e-03  5e-02 0:0.4\n      300    3000 2.413696640005903e-04 4.3e+01 9.57e-03  3e-04  7e-03 0:0.5\n      400    4000 1.271582136805314e-11 7.6e+01 9.70e-06  8e-08  3e-06 0:0.7\n      439    4390 1.062554035878040e-14 9.4e+01 5.31e-07  3e-09  8e-08 0:0.8\n    >>> es.result_pretty()  # pretty print result\n    termination on tolfun=1e-11\n    final/bestever f-value = 3.729752e-15 3.729752e-15\n    mean solution: [ 1.          1.          1.          1.          0.99999999  0.99999998\n      0.99999995  0.99999991]\n    std deviation: [  2.84303359e-09   2.74700402e-09   3.28154576e-09   5.92961588e-09\n       1.07700123e-08   2.12590385e-08   4.09374304e-08   8.16649754e-08]\n\noptimizes the 8-dimensional Rosenbrock function with initial solution all\nzeros and initial ``sigma = 0.5``.\n\nPretty much the same can be achieved a little less \"elaborate\" with::\n\n    >>> import cma\n    >>> xopt, es = cma.fmin2(cma.ff.rosen, 8 * [0], 0.5)\n        <output omitted>\n\nAnd a little more elaborate exposing the **ask-and-tell interface**::\n\n    >>> import cma\n    >>> es = cma.CMAEvolutionStrategy(12 * [0], 0.5)\n    >>> while not es.stop():\n    ...     solutions = es.ask()\n    ...     es.tell(solutions, [cma.ff.rosen(x) for x in solutions])\n    ...     es.logger.add()  # write data to disc to be plotted\n    ...     es.disp()\n        <output omitted>\n    >>> es.result_pretty()\n        <output omitted>\n    >>> cma.plot()  # shortcut for es.logger.plot()\n\n.. figure:: http://www.cmap.polytechnique.fr/~nikolaus.hansen/rosen12.png\n    :alt: CMA-ES on Rosenbrock function in dimension 8\n    :target: https://cma-es.github.io/cmaes_sourcecode_page.html#example\n    :align: center \n   \n    A single run on the 12-dimensional Rosenbrock function. \n\n\nThe ``CMAOptions`` class manages options for ``CMAEvolutionStrategy``,\ne.g. verbosity options can be found like::\n\n    >>> import cma\n    >>> cma.s.pprint(cma.CMAOptions('erb'))\n    {'verb_log': '1  #v verbosity: write data to files every verb_log iteration, writing can be time critical on fast to evaluate functions'\n     'verbose': '1  #v verbosity e.v. of initial/final message, -1 is very quiet, not yet implemented'\n     'verb_plot': '0  #v in fmin(): plot() is called every verb_plot iteration'\n     'verb_disp': '100  #v verbosity: display console output every verb_disp iteration'\n     'verb_filenameprefix': 'outcmaes  # output filenames prefix'\n     'verb_append': '0  # initial evaluation counter, if append, do not overwrite output files'\n     'verb_time': 'True  #v output timings on console'}\n\nOptions are passed like::\n\n    >>> import cma\n    >>> es = cma.CMAEvolutionStrategy(8 * [0], 0.5,\n                                      {'verb_disp': 1}) # display each iteration\n\n\nDocumentations\n--------------\nThe full package API documentation:\n\n* `version 3+`_ (recent)\n* `version 1.x`_\n\n.. _`version 3+`: https://cma-es.github.io/apidocs-pycma/\n.. _`version 1.x`: http://www.cmap.polytechnique.fr/~nikolaus.hansen/html-pythoncma/\n\nSee also\n\n* `Github page hosting this code`_ and its `FAQ`_ (under development)\n* `General CMA-ES source code page`_ with practical hints\n* `CMA-ES on Wikipedia`_\n\n.. _`Github page hosting this code`: https://github.com/CMA-ES/pycma\n.. _`FAQ`: https://github.com/CMA-ES/pycma/issues?q=is:issue+label:FAQ\n.. _`General CMA-ES source code page`: https://cma-es.github.io/cmaes_sourcecode_page.html\n.. _`CMA-ES on Wikipedia`: http://en.wikipedia.org/wiki/CMA-ES\n\nDependencies\n------------\n\n* required (unless for `cma.purecma`): ``numpy`` -- array processing for numbers, strings, records, and objects\n* optional (highly recommended): ``matplotlib`` -- Python plotting package (includes ``pylab``)\n\nUse ``pip install numpy`` etc. for installation. 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