[Python: Numpy n-th gradient (recursion)] #numpy #gradient #slope #recursion #np

grad_n.py

import numpy as np

def grad_n(y, x, n, edge_order=2):
    g = np.gradient(y, x, edge_order=edge_order)
    for _ in range(n-1):
        g = grad_n(g, x, 1, edge_order=edge_order)
    return g

test_grad_n.py

import unittest
import numpy as np

class TestGrad(unittest.TestCase):

    def test_grad(self):
        t = np.linspace(0, 6*np.pi, 10)
        y = 20*np.sin(t)
        gradienter = lambda x, y: np.gradient(y, x, edge_order=1)
        for i in range(5):
            if i == 0:
                g = gradienter(t, y)
            else:
                g = gradienter(t, g)
            gtest = utils._grad_n(y, t, i+1, edge_order=1)
            with self.subTest(self):
                self.assertTrue( (gtest == g).all() )