cython_minkowski.pyx

%%cython

# Minkowski Distance with p=0.5
# based on scikit-learn MinkowskiDistance cython's class
# https://github.com/scikit-learn/scikit-learn/blob/cbd3bca20f1d19461011b5f59d9416669eb30535/sklearn/neighbors/dist_metrics.pyx#L524


from libc.math cimport fabs, sqrt, pow
cimport numpy as np

from typedefs cimport DTYPE_t, ITYPE_t, DITYPE_t

cdef inline DTYPE_t minkowski_05(DTYPE_t* x1, DTYPE_t* x2, ITYPE_t size) nogil except -1:
    cdef DTYPE_t d = 0
    cdef np.intp_t j
    for j in range(size):
        d += sqrt(fabs(x1[j] - x2[j]))

    return pow(d, 2.0)

import cython
import numpy as np

@cython.boundscheck(False)
@cython.wraparound(False)
def minkowski_05_py(np.ndarray[np.float64_t, ndim=1, mode = 'c'] x, np.ndarray[np.float64_t, ndim=1, mode = 'c'] y):
    return minkowski_05(&x[0], &y[0], x.shape[0])