numba_parallel.ipynb

by adding a new module with the following function, which operates on a single point instead of an array:

%%file numba_parallel.py
import numba
from numba import jit
import numpy as np

@cc.export('ray_tracing1',  'b1(f8, f8, f8[:,:])')
@jit(nopython=True, nogil=True)
def ray_tracing1(x,y,poly):
    n = len(poly)
    inside = False
    p2x = 0.0
    p2y = 0.0
    xints = 0.0
    p1x,p1y = poly[0]
    for i in range(n+1):
        p2x,p2y = poly[i % n]
        if y > min(p1y,p2y):
            if y <= max(p1y,p2y):
                if x <= max(p1x,p2x):
                    if p1y != p2y:
                        xints = (y-p1y)*(p2x-p1x)/(p2y-p1y)+p1x
                    if p1x == p2x or x <= xints:
                        inside = not inside
        p1x,p1y = p2x,p2y

    return inside

I can define then a new function that make use of numba.prange to loop over all the points in parallel:

import numba

@numba.njit(parallel=True)
def parallel_tracing(pp, poly):
    D = np.empty(len(pp), dtype=numba.boolean)
    for i in numba.prange(1, len(D) - 1):
        D[i] = nbspatial.ray_tracing1(pp[i][0], pp[i][1], polygon)
    return D