PyJulia Example Use Case

create_points.py

import numpy as np

r = np.arange(1.0, 11.0, 0.1)

n = len(r)**3
pts = np.empty((n, 3))
i = 0
for x in r:
    for y in r:
        for z in r:
            pts[i,:] = [x, y, z]
            i += 1

np.savetxt("points.csv", pts, delimiter=",")

new.jl

function force(x, y, z)
    r2 = x^2 + y^2 + z^2
    n = sqrt(r2)
    return [x/(n*r2), y/(n*r2), z/(n*r2)]
end

function force_sum(pts)
    s = zeros(3)
    @time for i in 1:size(pts, 1) # ~0.3 seconds
        s += force(pts[i,:]...)
    end
    return s
end

new_ideal.py

import numpy as np
import time
import julia

j = julia.Julia()
j.include("new.jl")

pts = np.genfromtxt("points.csv", delimiter=',')

start = time.time()
j.force_sum(pts)
end = time.time()
print(end-start) # ideally with small overhead (~0.4 seconds)

print(s)

# do some more processing in python

new_working.py

import numpy as np
import time
import julia

j = julia.Julia()
force_sum = j.evalfile("new.jl")

pts = np.genfromtxt("points.csv", delimiter=',')

start = time.time()
s = force_sum(pts)
end = time.time()
print(end-start) # ~3 seconds

print(s)

# do some more processing in python

original.py

import numpy as np
import time

def force(x, y, z):
    r2 = x**2 + y**2 + z**2
    n = sqrt(r2)
    return (x/(n*r2), y/(n*r2), z/(n*r2))

pts = np.genfromtxt("points.csv", delimiter=',')
s = np.array([0.0, 0.0, 0.0])

start = time.time()
for i in range(len(pts)):
    s += force(pts[i,0], pts[i,1], pts[i,2])
end = time.time()
print(end-start) # ~6 seconds

print(s)

# do some more processing in python