I'm still trying to subclass ndarray in Pyrex, without much success so far. I started to follow Francesc's suggestion (http://projects.scipy.org/pipermail/numpy-discussion/2007-January/025644.htm...), but that doesn't fit what I need: the myarray class Francesc introduced is just an object, not a subclass of ndarray... The closest I came to something vaguely running is the following (called subnd.pyx later on): #------------------- from definitions cimport import_array, \ malloc, free, npy_intp, \ PyArray_GETITEM, PyArray_EMPTY, \ ndarray, dtype # NumPy must be initialized import_array() import numpy as _N cdef class Sub_2(ndarray): cdef readonly object _info cdef ndarray __mask def __new__(self, object shape=None, object dtype=None, object buffer=None, object order=None, object infodict={}): self.__mask = <ndarray>_N.zeros(shape, _N.bool) self._info = infodict return property info: def __get__(self): return self._info def __set__(self, value): self._info = value property _mask: def __get__(self): return self.__mask def subarray(obj, info={}): _obj = <ndarray>_N.asarray(obj) print "_obj is: %s" % _obj _internal = Sub_2(shape=_obj.shape, dtype=_obj.dtype) _internal.flat[:] = _obj.flat[:] _internal.info = info return _internal #---------------------- However, I get a segfault when I try to play with it in Python:

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import numpy as N import subnd L = N.array([1,2,3] x = subarray(L) x Sub_2([1, 2, 3]) x+1 Sub_2([2, 3, 4]) N.log(x) crash

So obviously I'm missing something, but what ? Some kind of closure ? Moreover, I'm a bit disappointed with this method: if I understand correctly the subtleties of subclassing in pyrex, the ndarray.__new__ is called before Sub_2.__new__, with the same arguments. As ndarray.__new__ doesn't take optional arguments, the subclass can't either. That's a bit limiting, I have to call the constructor function all the time... I'm completely at loss, here. Any advice/help/suggestions would be more than welcome.