Question

I have an array of float values that is created in regular Python, that I want to pass to a cython function that fronts for an underlying C function.
The C function requires the array to be passed as a floating pointer as in:

void setOverlays(const float * verts);

the cython wrapper looks like this:

def set_overlays(verts):
    setOverlays(verts)

How can I make verts into a cython array?
I thought that this might work:

cdef float * cVerts = [v for v in verts]

but unfortunately the value generated is a Python object and in this case automatic conversion does not work.

The equivalent expression(that works) in ctypes is:

cVerts = (c_float * len(verts))()
for i in range(len(verts)):
    cVerts[i] = verts[i]
setOverlays(cast(byteref(cVerts), POINTER(c_float)))

I am trying to achieve the same thing, but in cython

Thanks in advance!

Answer 1

I found the Cython specific way:

cdef float* cVerts = []
    for i in xrange(len(verts)):
        cVerts[i] = verts[i]
setOverlays(cVerts)

Interestingly enough the above two solutions were rejected by the cython compiler.