wydh / gsw-python

Python implementation of TEOS-10 GSW based on ufunc wrappers of GSW-C

gsw Python package

This Python implementation of the Thermodynamic Equation of Seawater 2010 (TEOS-10) is based primarily on numpy ufunc wrappers of the GSW-C implementation. We expect it to replace the original python-gsw pure-python implementation after a brief overlap period. The primary reasons for this change are that by building on the C implementation we reduce code duplication and we gain an immediate update to the 75-term equation. Additional benefits include a major increase in speed, a reduction in memory usage, and the inclusion of more functions. The penalty is that a C (or MSVC C++ for Windows) compiler is required to build the package from source.

Warning: this is for Python >=3.5 only.

Documentation is provided at https://teos-10.github.io/GSW-Python/.

For the core functionality, we use an auto-generated C extension module to wrap the C functions as numpy ufuncs, and then use an autogenerated Python module to add docstrings and handle masked arrays. 165 scalar C functions with only double-precision arguments and return values are wrapped as ufuncs, and 158 of these are exposed in the gsw namespace with an additional wrapper in Python.

A hand-written wrapper is used for one C function, and others are re-implemented directly in Python instead of being wrapped. Additional functions present in GSW-Matlab but not in GSW-C may be re-implemented in Python, but there is no expectation that all such functions will be provided.

The package can be installed from a clone of the repo using pip install .. It is neither necessary nor recommended to run the code generators, and no instructions are provided for them; their output is included in the repo. You will need a suitable compiler: gcc or clang for unix-like systems, or the MSVC compiler set used for Python itself on Windows. For Windows, some of the source code has been modified to C++ because the MSVC C compiler does not support the C99 complex data type used in original GSW-C.

To test, after installation, run "pytest" from the source directory.