  The Standards of Fundamental Astronomy (SOFA) is a service provided by the
International Astronomical Union (IAU) that offers algorithms and software for
astronomical calculations, which was released in two versions by FORTRAN 77 and
ANSI C, respectively. In this work, we implement the python package PyMsOfa for
SOFA service by three ways: (1) a python wrapper package based on a foreign
function library for Python (ctypes), (2) a python wrapper package with the
foreign function interface for Python calling C code (cffi), and (3) a python
package directly written in pure python codes from SOFA subroutines. The
package PyMsOfa has fully implemented 247 functions of the original SOFA
routines. In addition, PyMsOfa is also extensively examined, which is exactly
consistent with those test examples given by the original SOFA. This python
package can be suitable to not only the astrometric detection of habitable
planets of the Closeby Habitable Exoplanet Survey (CHES) mission (Ji et al.
2022), but also for the frontiers themes of black holes and dark matter related
to astrometric calculations and other fields. The source codes are available
via https://github.com/CHES2023/PyMsOfa.
