Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/scipy/linalg/tests/test_sketches.py

@@ -0,0 +1,118 @@
+"""Tests for _sketches.py."""
+
+import numpy as np
+from numpy.testing import assert_, assert_equal
+from scipy.linalg import clarkson_woodruff_transform
+from scipy.linalg._sketches import cwt_matrix
+from scipy.sparse import issparse, rand
+from scipy.sparse.linalg import norm
+
+
+class TestClarksonWoodruffTransform(object):
+    """
+    Testing the Clarkson Woodruff Transform
+    """
+    # set seed for generating test matrices
+    rng = np.random.RandomState(seed=1179103485)
+
+    # Test matrix parameters
+    n_rows = 2000
+    n_cols = 100
+    density = 0.1
+
+    # Sketch matrix dimensions
+    n_sketch_rows = 200
+
+    # Seeds to test with
+    seeds = [1755490010, 934377150, 1391612830, 1752708722, 2008891431,
+             1302443994, 1521083269, 1501189312, 1126232505, 1533465685]
+
+    A_dense = rng.randn(n_rows, n_cols)
+    A_csc = rand(
+        n_rows, n_cols, density=density, format='csc', random_state=rng,
+    )
+    A_csr = rand(
+        n_rows, n_cols, density=density, format='csr', random_state=rng,
+    )
+    A_coo = rand(
+        n_rows, n_cols, density=density, format='coo', random_state=rng,
+    )
+
+    # Collect the test matrices
+    test_matrices = [
+        A_dense, A_csc, A_csr, A_coo,
+    ]
+
+    # Test vector with norm ~1
+    x = rng.randn(n_rows, 1) / np.sqrt(n_rows)
+
+    def test_sketch_dimensions(self):
+        for A in self.test_matrices:
+            for seed in self.seeds:
+                sketch = clarkson_woodruff_transform(
+                    A, self.n_sketch_rows, seed=seed
+                )
+                assert_(sketch.shape == (self.n_sketch_rows, self.n_cols))
+
+    def test_seed_returns_identical_transform_matrix(self):
+        for A in self.test_matrices:
+            for seed in self.seeds:
+                S1 = cwt_matrix(
+                    self.n_sketch_rows, self.n_rows, seed=seed
+                ).todense()
+                S2 = cwt_matrix(
+                    self.n_sketch_rows, self.n_rows, seed=seed
+                ).todense()
+                assert_equal(S1, S2)
+
+    def test_seed_returns_identically(self):
+        for A in self.test_matrices:
+            for seed in self.seeds:
+                sketch1 = clarkson_woodruff_transform(
+                    A, self.n_sketch_rows, seed=seed
+                )
+                sketch2 = clarkson_woodruff_transform(
+                    A, self.n_sketch_rows, seed=seed
+                )
+                if issparse(sketch1):
+                    sketch1 = sketch1.todense()
+                if issparse(sketch2):
+                    sketch2 = sketch2.todense()
+                assert_equal(sketch1, sketch2)
+
+    def test_sketch_preserves_frobenius_norm(self):
+        # Given the probabilistic nature of the sketches
+        # we run the test multiple times and check that
+        # we pass all/almost all the tries.
+        n_errors = 0
+        for A in self.test_matrices:
+            if issparse(A):
+                true_norm = norm(A)
+            else:
+                true_norm = np.linalg.norm(A)
+            for seed in self.seeds:
+                sketch = clarkson_woodruff_transform(
+                    A, self.n_sketch_rows, seed=seed,
+                )
+                if issparse(sketch):
+                    sketch_norm = norm(sketch)
+                else:
+                    sketch_norm = np.linalg.norm(sketch)
+
+                if np.abs(true_norm - sketch_norm) > 0.1 * true_norm:
+                    n_errors += 1
+        assert_(n_errors == 0)
+
+    def test_sketch_preserves_vector_norm(self):
+        n_errors = 0
+        n_sketch_rows = int(np.ceil(2. / (0.01 * 0.5**2)))
+        true_norm = np.linalg.norm(self.x)
+        for seed in self.seeds:
+            sketch = clarkson_woodruff_transform(
+                self.x, n_sketch_rows, seed=seed,
+            )
+            sketch_norm = np.linalg.norm(sketch)
+
+            if np.abs(true_norm - sketch_norm) > 0.5 * true_norm:
+                n_errors += 1
+        assert_(n_errors == 0)