TEST: rewrite tests for sinc_decimate()

Author: ggventurini

deltasigma/tests/test_sinc_decimate.py

@@ -1,35 +1,3 @@
-# -*- coding: utf-8 -*-
-# _sinc_decimate.py
-# This module provides the sinc_decimate function.
-# Copyright 2013 Giuseppe Venturini
-# This file is part of python-deltasigma.
-#
-# python-deltasigma is a 1:1 Python replacement of Richard Schreier's 
-# MATLAB delta sigma toolbox (aka "delsigma"), upon which it is heavily based.
-# The delta sigma toolbox is (c) 2009, Richard Schreier.
-#
-# python-deltasigma is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# LICENSE file for the licensing terms.
-
-"""This module provides the sinc_decimate() function, which decimates a vector 
-by a sinc filter of specified order and length.
-"""
-
-from __future__ import division
-import numpy as np
-
-def sinc_decimate(x, m, r):
-    """Decimate ``x`` by an ``m``-th order sinc filter of length ``r``.
-    """
-    x = x[:]
-    for _ in range(m):
-        x = np.cumsum(x)
-        x = np.concatenate((x[:r], x[r:] - x[:-r]), axis=0)/r
-    return x[r::r]
-
-
 # -*- coding: utf-8 -*-
 # test_sinc_decimate.py
 # This module provides the tests for the sinc_decimate function.
@@ -55,14 +23,21 @@ def sinc_decimate(x, m, r):
 class TestSincDecimate(unittest.TestCase):
     """Test class for sinc_decimate()"""
 
-    def setUp(self):
-        self.r = [-1.33907057e-17, -3.55951662e-17, -2.28847549e-18,
-                  -3.55951662e-17, -1.02208548e-16, -4.35275455e-16,
-                  4.97311886e-16, -4.57479916e-16, 4.30698504e-16]
-
-    def test_sinc_decimate(self):
-        """Test function for sinc_decimate()"""
-        tv = np.sin(2*np.pi*.1*np.arange(0, 100))
-        res = ds.sinc_decimate(tv, 1, 10)
-        self.assertTrue(np.allclose(res, self.r, rtol=1e-5, atol=1e-8))
+    def test_sinc_decimate_1(self):
+        """Test function for sinc_decimate() 1/3"""
+        x = [1]*10
+        self.assertTrue(np.allclose(ds.sinc_decimate(x, 1, 10), [1.]))
+
+    def test_sinc_decimate_2(self):
+        """Test function for sinc_decimate() 2/3"""
+        x = [1]*10
+        self.assertTrue(np.allclose(ds.sinc_decimate(x, 2, 5), [.6, 1.]))
+
+    def test_sinc_decimate_3(self):
+        """Test function for sinc_decimate() 3/3"""
+        x = [1]*10
+        x = np.cumsum(np.asarray(x))
+        self.assertTrue(np.allclose(ds.sinc_decimate(x, 1, 5), [3., 8.]))
+        self.assertTrue(np.allclose(ds.sinc_decimate(x, 2, 5), [1.4, 6.]))
+        self.assertTrue(np.allclose(ds.sinc_decimate(x, 3, 3), [0.55555556, 3., 6.]))