============================
``ctypes`` Utility Functions
============================
See Also
---------
load_library : Load a C library.
ndpointer : Array restype/argtype with verification.
as_ctypes : Create a ctypes array from an ndarray.
as_array : Create an ndarray from a ctypes array.
References
----------
.. [1] "SciPy Cookbook: ctypes", http://www.scipy.org/Cookbook/Ctypes
Examples
--------
Load the C library:
>>> _lib = np.ctypeslib.load_library('libmystuff', '.') #DOCTEST: +ignore
Our result type, an ndarray that must be of type double, be 1-dimensional
and is C-contiguous in memory:
>>> array_1d_double = np.ctypeslib.ndpointer(
... dtype=np.double,
... ndim=1, flags='CONTIGUOUS') #DOCTEST: +ignore
Our C-function typically takes an array and updates its values
in-place. For example::
void foo_func(double* x, int length)
{
int i;
for (i = 0; i < length; i++) {
x[i] = i*i;
}
}
We wrap it using:
>>> lib.foo_func.restype = None #DOCTEST: +ignore
>>> lib.foo.argtypes = [array_1d_double, c_int] #DOCTEST: +ignore
Then, we're ready to call ``foo_func``:
>>> out = np.empty(15, dtype=np.double)
>>> _lib.foo_func(out, len(out)) #DOCTEST: +ignore
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