如何在cython中声明全局numpy.ndarray？

Question

I want to create a signal processing algorithm that needs to hold some internal state in a numpy array.

For speed, I coded that in cython and declared the state a global variable like this:

import numpy as np
cimport numpy  as np
cdef np.ndarray delay_buffer

However, what I really would like to do is this:

import numpy as np
cimport numpy as np
DTYPE = np.float32
ctypedef np.float32_t DTYPE_t
cdef np.ndarray[DTYPE_t] delay_buffer

This I can do anyhwere else, but not in the global scope. Is there any way to accomplish this?

Answer 1

Is there any way to accomplish this?

No. As the error says, Buffer types only allowed as function local variables .

One alternative is to use a monolithic main function. This really only takes indenting everything but it means that you can only share so much.

My favourite alternative would be to upgrade to the modern method of using memoryviews:

cdef DTYPE_t[:] delay_buffer

The should be faster, cleaner and no less powerful.