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Metadata-Version: 2.1 |
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Name: numexpr |
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Version: 2.10.0 |
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Summary: Fast numerical expression evaluator for NumPy |
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Home-page: https://github.com/pydata/numexpr |
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Author: David M. Cooke, Francesc Alted, and others |
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Maintainer: Francesc Alted |
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Maintainer-email: [email protected] |
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License: MIT |
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Classifier: Development Status :: 6 - Mature |
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Classifier: Intended Audience :: Financial and Insurance Industry |
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Classifier: Intended Audience :: Science/Research |
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Classifier: License :: OSI Approved :: MIT License |
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Classifier: Programming Language :: Python :: 3 |
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Classifier: Programming Language :: Python :: 3.9 |
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Classifier: Programming Language :: Python :: 3.10 |
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Classifier: Programming Language :: Python :: 3.11 |
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Classifier: Programming Language :: Python :: 3.12 |
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Classifier: Operating System :: Microsoft :: Windows |
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Classifier: Operating System :: POSIX |
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Classifier: Operating System :: MacOS |
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Requires-Python: >=3.9 |
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Description-Content-Type: text/x-rst |
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License-File: LICENSE.txt |
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License-File: AUTHORS.txt |
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Requires-Dist: numpy >=1.19.3 |
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====================================================== |
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NumExpr: Fast numerical expression evaluator for NumPy |
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====================================================== |
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:Author: David M. Cooke, Francesc Alted, and others. |
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:Maintainer: Francesc Alted |
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:Contact: [email protected] |
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:URL: https://github.com/pydata/numexpr |
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:Documentation: http://numexpr.readthedocs.io/en/latest/ |
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:GitHub Actions: |actions| |
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:PyPi: |version| |
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:DOI: |doi| |
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:readthedocs: |docs| |
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.. |actions| image:: https://github.com/pydata/numexpr/workflows/Build/badge.svg |
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:target: https://github.com/pydata/numexpr/actions |
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.. |travis| image:: https://travis-ci.org/pydata/numexpr.png?branch=master |
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:target: https://travis-ci.org/pydata/numexpr |
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.. |docs| image:: https://readthedocs.org/projects/numexpr/badge/?version=latest |
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:target: http://numexpr.readthedocs.io/en/latest |
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.. |doi| image:: https://zenodo.org/badge/doi/10.5281/zenodo.2483274.svg |
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:target: https://doi.org/10.5281/zenodo.2483274 |
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.. |version| image:: https://img.shields.io/pypi/v/numexpr |
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:target: https://pypi.python.org/pypi/numexpr |
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What is NumExpr? |
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---------------- |
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NumExpr is a fast numerical expression evaluator for NumPy. With it, |
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expressions that operate on arrays (like :code:`'3*a+4*b'`) are accelerated |
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and use less memory than doing the same calculation in Python. |
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In addition, its multi-threaded capabilities can make use of all your |
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cores -- which generally results in substantial performance scaling compared |
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to NumPy. |
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Last but not least, numexpr can make use of Intel's VML (Vector Math |
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Library, normally integrated in its Math Kernel Library, or MKL). |
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This allows further acceleration of transcendent expressions. |
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How NumExpr achieves high performance |
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------------------------------------- |
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The main reason why NumExpr achieves better performance than NumPy is |
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that it avoids allocating memory for intermediate results. This |
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results in better cache utilization and reduces memory access in |
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general. Due to this, NumExpr works best with large arrays. |
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NumExpr parses expressions into its own op-codes that are then used by |
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an integrated computing virtual machine. The array operands are split |
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into small chunks that easily fit in the cache of the CPU and passed |
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to the virtual machine. The virtual machine then applies the |
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operations on each chunk. It's worth noting that all temporaries and |
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constants in the expression are also chunked. Chunks are distributed among |
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the available cores of the CPU, resulting in highly parallelized code |
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execution. |
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The result is that NumExpr can get the most of your machine computing |
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capabilities for array-wise computations. Common speed-ups with regard |
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to NumPy are usually between 0.95x (for very simple expressions like |
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:code:`'a + 1'`) and 4x (for relatively complex ones like :code:`'a*b-4.1*a > 2.5*b'`), |
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although much higher speed-ups can be achieved for some functions and complex |
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math operations (up to 15x in some cases). |
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NumExpr performs best on matrices that are too large to fit in L1 CPU cache. |
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In order to get a better idea on the different speed-ups that can be achieved |
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on your platform, run the provided benchmarks. |
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Installation |
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------------ |
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From wheels |
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^^^^^^^^^^^ |
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NumExpr is available for install via `pip` for a wide range of platforms and |
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Python versions (which may be browsed at: https://pypi.org/project/numexpr/#files). |
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Installation can be performed as:: |
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pip install numexpr |
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If you are using the Anaconda or Miniconda distribution of Python you may prefer |
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to use the `conda` package manager in this case:: |
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conda install numexpr |
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From Source |
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^^^^^^^^^^^ |
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On most \*nix systems your compilers will already be present. However if you |
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are using a virtual environment with a substantially newer version of Python than |
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your system Python you may be prompted to install a new version of `gcc` or `clang`. |
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For Windows, you will need to install the Microsoft Visual C++ Build Tools |
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(which are free) first. The version depends on which version of Python you have |
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installed: |
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https://wiki.python.org/moin/WindowsCompilers |
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For Python 3.6+ simply installing the latest version of MSVC build tools should |
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be sufficient. Note that wheels found via pip do not include MKL support. Wheels |
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available via `conda` will have MKL, if the MKL backend is used for NumPy. |
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See `requirements.txt` for the required version of NumPy. |
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NumExpr is built in the standard Python way:: |
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python setup.py build install |
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You can test `numexpr` with:: |
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python -c "import numexpr; numexpr.test()" |
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Do not test NumExpr in the source directory or you will generate import errors. |
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Enable Intel® MKL support |
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^^^^^^^^^^^^^^^^^^^^^^^^^ |
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NumExpr includes support for Intel's MKL library. This may provide better |
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performance on Intel architectures, mainly when evaluating transcendental |
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functions (trigonometrical, exponential, ...). |
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If you have Intel's MKL, copy the `site.cfg.example` that comes with the |
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distribution to `site.cfg` and edit the latter file to provide correct paths to |
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the MKL libraries in your system. After doing this, you can proceed with the |
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usual building instructions listed above. |
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Pay attention to the messages during the building process in order to know |
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whether MKL has been detected or not. Finally, you can check the speed-ups on |
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your machine by running the `bench/vml_timing.py` script (you can play with |
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different parameters to the `set_vml_accuracy_mode()` and `set_vml_num_threads()` |
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functions in the script so as to see how it would affect performance). |
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Usage |
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----- |
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:: |
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>>> import numpy as np |
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>>> import numexpr as ne |
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>>> a = np.arange(1e6) # Choose large arrays for better speedups |
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>>> b = np.arange(1e6) |
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>>> ne.evaluate("a + 1") # a simple expression |
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array([ 1.00000000e+00, 2.00000000e+00, 3.00000000e+00, ..., |
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9.99998000e+05, 9.99999000e+05, 1.00000000e+06]) |
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>>> ne.evaluate("a * b - 4.1 * a > 2.5 * b") # a more complex one |
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array([False, False, False, ..., True, True, True], dtype=bool) |
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>>> ne.evaluate("sin(a) + arcsinh(a/b)") # you can also use functions |
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array([ NaN, 1.72284457, 1.79067101, ..., 1.09567006, |
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0.17523598, -0.09597844]) |
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>>> s = np.array([b'abba', b'abbb', b'abbcdef']) |
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>>> ne.evaluate("b'abba' == s") # string arrays are supported too |
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array([ True, False, False], dtype=bool) |
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Documentation |
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------------- |
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Please see the official documentation at `numexpr.readthedocs.io <https://numexpr.readthedocs.io>`_. |
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Included is a user guide, benchmark results, and the reference API. |
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Authors |
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------- |
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Please see `AUTHORS.txt <https://github.com/pydata/numexpr/blob/master/AUTHORS.txt>`_. |
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License |
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------- |
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NumExpr is distributed under the `MIT <http://www.opensource.org/licenses/mit-license.php>`_ license. |
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.. Local Variables: |
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.. mode: text |
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.. coding: utf-8 |
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.. fill-column: 70 |
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.. End: |
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