Any way to create a NumPy matrix with C API?
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05-09-2019 - |
Question
I read the documentation on NumPy C API I could find, but still wasn't able to find out whether there is a possibility to construct a matrix object with C API — not a two-dimensional array. The function is intended for work with math matrices, and I don't want strange results if the user calls matrix multiplication forgetting to convert this value from an array to a matrix (multiplication and exponentiation being the only difference that matrix subclass has).
Solution
numpy.matrix
is an ordinary class defined in numpy/core/defmatrix.py. You can construct it using C API as any other instance of user-defined class in Python.
OTHER TIPS
You can call any python callable with the PyObject_Call*
functions.
PyObject *numpy = PyImport_ImportModule("numpy");
PyObject *numpy_matrix = PyObject_GetAttrString(numpy, "matrix");
PyObject *my_matrix = PyObject_CallFunction(numpy_matrix, "(s)", "0 0; 0 0");
This will create a matrix my_matrix
of size 2x2.
EDIT: Changed references to numpy.zeros
/numpy.ndarray
to numpy.matrix
instead.
I also found a good tutorial on the subject: http://starship.python.net/crew/hinsen/NumPyExtensions.html