C-Types Foreign Function Interface (
- numpy.ctypeslib.as_array(obj, shape=None)#
Create a numpy array from a ctypes array or POINTER.
The numpy array shares the memory with the ctypes object.
The shape parameter must be given if converting from a ctypes POINTER. The shape parameter is ignored if converting from a ctypes array
Create and return a ctypes object from a numpy array. Actually anything that exposes the __array_interface__ is accepted.
Convert a dtype into a ctypes type.
The dtype to convert
A ctype scalar, union, array, or struct
If the conversion is not possible
This function does not losslessly round-trip in either direction.
insert padding fields
reorder fields to be sorted by offset
discard field titles
- numpy.ctypeslib.load_library(libname, loader_path)#
It is possible to load a library using
>>> lib = ctypes.cdll[<full_path_name>]
But there are cross-platform considerations, such as library file extensions, plus the fact Windows will just load the first library it finds with that name. NumPy supplies the load_library function as a convenience.
Changed in version 1.20.0: Allow libname and loader_path to take any path-like object.
Name of the library, which can have ‘lib’ as a prefix, but without an extension.
Where the library can be found.
- ctypes.cdll[libpath]library object
A ctypes library object
If there is no library with the expected extension, or the library is defective and cannot be loaded.
- numpy.ctypeslib.ndpointer(dtype=None, ndim=None, shape=None, flags=None)#
An ndpointer instance is used to describe an ndarray in restypes and argtypes specifications. This approach is more flexible than using, for example,
POINTER(c_double), since several restrictions can be specified, which are verified upon calling the ctypes function. These include data type, number of dimensions, shape and flags. If a given array does not satisfy the specified restrictions, a
- dtypedata-type, optional
- ndimint, optional
Number of array dimensions.
- shapetuple of ints, optional
- flagsstr or tuple of str
Array flags; may be one or more of:
C_CONTIGUOUS / C / CONTIGUOUS
F_CONTIGUOUS / F / FORTRAN
OWNDATA / O
WRITEABLE / W
ALIGNED / A
WRITEBACKIFCOPY / X
- klassndpointer type object
A type object, which is an
_ndtprinstance containing dtype, ndim, shape and flags information.
If a given array does not satisfy the specified restrictions.
>>> clib.somefunc.argtypes = [np.ctypeslib.ndpointer(dtype=np.float64, ... ndim=1, ... flags='C_CONTIGUOUS')] ... >>> clib.somefunc(np.array([1, 2, 3], dtype=np.float64)) ...