[Python] Using numpy.array in cython

I want to rewrite a class in cython format and save it as demo.pyx. The input parameter for the class would be either a 2D np.array with an Nx2 shape, e.g. a=np.array([[0.2,-0.8],[3.7,0.02],..,[-0.92,-3.33]]), or a list for instance a=[0.1,2.7].

cimport numpy as np
DTYPE = np.float64
ctypedef np.float64_t DTYPE_t
cdef class halo_positions(object):
cdef unsigned double *x
cdef unsigned double *y
def __init__(self, np.ndarray[np.float64_t,ndim=2,mode='c'] positions):
self.x = &positions[:,0]
self.y = &positions[:,1]


What I have tried to write causes error message as following:

running build_ext
cythoning demo.pyx to demo.c

Error compiling Cython file:
------------------------------------------------------------
...
cimport numpy as np
DTYPE = np.float64
ctypedef np.float64_t DTYPE_t
cdef class halo_positions(object):
cdef unsigned double *x
^
------------------------------------------------------------

demo.pyx:5:9: Unrecognised type modifier combination

Error compiling Cython file:
------------------------------------------------------------
...
cimport numpy as np
DTYPE = np.float64
ctypedef np.float64_t DTYPE_t
cdef class halo_positions(object):
cdef unsigned double *x
cdef unsigned double *y
^
------------------------------------------------------------

demo.pyx:6:9: Unrecognised type modifier combination

Error compiling Cython file:
------------------------------------------------------------
...
ctypedef np.float64_t DTYPE_t
cdef class halo_positions(object):
cdef unsigned double *x
cdef unsigned double *y
def __init__(self, np.ndarray[np.float64_t,ndim=2,mode='c'] positions):
self.x = &positions[:,0]
^
------------------------------------------------------------

demo.pyx:8:17: Cannot take address of Python variable

Error compiling Cython file:
------------------------------------------------------------
...
cdef class halo_positions(object):
cdef unsigned double *x
cdef unsigned double *y
def __init__(self, np.ndarray[np.float64_t,ndim=2,mode='c'] positions):
self.x = &positions[:,0]
self.y = &positions[:,1]
^
------------------------------------------------------------

demo.pyx:9:17: Cannot take address of Python variable


I know there is a problem with the way I have used pointers, but if I want to keep the type of x and y ambiguous, I need to use this. How could I make my class work?

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