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libs/geographiclib/wrapper/python/README.md

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+# Calling the GeographicLib C++ library from Python
+
+The geodesic routines in GeographicLib have been implemented as a
+[native Python library](http://pypi.python.org/pypi/geographiclib).
+For documentation see
+
+  https://geographiclib.sourceforge.io/Python/doc/
+
+## boost-python
+
+It is also possible to call the C++ version of GeographicLib directly
+from Python and this directory contains a small example,
+`PyGeographicLib.cpp`, which uses boost-python and the `Geoid` class to
+convert heights above the geoid to heights above the ellipsoid.  More
+information on calling boost-python, see
+
+  https://www.boost.org/doc/libs/release/libs/python
+
+To build and install this interface, do
+```bash
+mkdir BUILD
+cd BUILD
+cmake -D CMAKE_INSTALL_PREFIX=~/.local ..
+make
+make install
+```
+This assumes that you have installed GeographicLib somewhere that cmake
+can find it.  If you want just to use the version of GeographicLib that
+you have built in the top-level BUILD directory, include, e.g.,
+```bash
+-D GeographicLib_DIR=../../BUILD
+```
+in the invocation of cmake (the directory is relative to the source
+directory, wrapper/python).
+
+`make install` installs PyGeographicLib in
+```
+~/.local/lib/python2.7/site-packages
+```
+which is in the default search path for python 2.7.  To convert 20m
+above the geoid at 42N 75W to a height above the ellipsoid, do
+```python
+$ python
+>>> from PyGeographicLib import Geoid
+>>> geoid = Geoid("egm2008-1")
+>>> geoid.EllipsoidHeight(42, -75, 20)
+-10.671887499999997
+>>> help(Geoid.EllipsoidHeight)
+```
+
+Notes:
+
+* The geoid data (`egm2008-1`) should be installed somewhere that
+  GeographicLib knows about.
+
+* This prescription applies to Linux machines.  Similar steps can be
+  used on Windows and MacOSX machines.
+
+* You will need the packages boost-python, boost-devel, python, and
+  python-devel installed.
+
+* `CMakeLists.txt` specifies the version of python to look for (version
+  2.7).  This must match that used in boost-python.  To check do, e.g.,
+  ```bash
+  ldd /usr/lib64/libboost_python.so
+  ```
+
+* `CMakeLists.txt` looks for a shared-library version of GeographicLib.
+  This is the default with cmake build on non-Windows platforms.  On
+  Windows, use the cmake option `-D BUILD_SHARED_LIBS=ON` to specify
+  building a shared library.
+
+Acknowledgment:
+
+Thanks to Jonathan Takahashi <jtakahashi@gmail.com> for the sample code
+in PyGeographicLib.cpp and the commands needed to compile and link this.
+
+## Cython
+
+An alternative to boost-python is provided by [Cython](https::/cython.org).
+Sergey Serebryakov offers the github project
+
+  https://github.com/megaserg/geographiclib-cython-bindings
+
+which provides a fast python interface to the geodesic routines.