Merge pull request #701 from larseeri/kron

theano/sandbox/linalg/kron.py

+import numpy
+import theano
+from theano.gof import Op, Apply
+from theano import tensor
+
+try:
+    import scipy.linalg
+    imported_scipy = True
+except ImportError:
+    imported_scipy = False
+
+
+class Kron(Op):
+    """
+    Kronecker product of a and b.
+
+    Parameters:
+
+    a: array, shape (M, N)
+    b: array, shape (P, Q)
+
+    Returns:
+
+    A: array, shape (M*P, N*Q)
+
+    The result is the block matrix:
+    (notice that a[i,j]*b is itself a matrix of the same shape as b)
+
+    a[0,0]*b    a[0,1]*b  ... a[0,-1]*b
+    a[1,0]*b    a[1,1]*b  ... a[1,-1]*b
+    ...
+    a[-1,0]*b   a[-1,1]*b ... a[-1,-1]*b
+    """
+
+    def __eq__(self, other):
+        return type(self) == type(other)
+
+    def __hash__(self):
+        return hash(type(self))
+
+    def __str__(self):
+        return "%s" % self.__class__.__name__
+
+    def make_node(self, a, b):
+        assert imported_scipy, (
+            "Scipy not available. Scipy is needed for the Kron op")
+        a = tensor.as_tensor_variable(a)
+        b = tensor.as_tensor_variable(b)
+
+        if (not a.ndim == 2 or not b.ndim == 2):
+            raise TypeError('%s: inputs must have two dimensions' %
+                            self.__class__.__name__)
+
+        out_var = tensor.TensorType(dtype=theano.scalar.upcast(a, b),
+                                     broadcastable=(False, False))()
+        return Apply(self, [a, b], [out_var])
+
+    def infer_shape(self, node, in_shapes):
+        shape_a, shape_b = in_shapes
+        return [[shape_a[0] * shape_b[0], shape_a[1] * shape_b[1]]]
+
+    def perform(self, node, inputs, output_storage):
+        a, b = inputs
+        output_storage[0][0] = scipy.linalg.kron(a, b)
+
+    def grad(self, inputs, cost_grad):
+        raise NotImplementedError('%s: gradient is not currently'
+                ' implemented' % self.__class__.__name__)
+
+kron = Kron()

theano/sandbox/linalg/tests/test_kron.py

+import numpy
+from theano import tensor, function
+from theano.tests import unittest_tools as utt
+from theano.sandbox.linalg.kron import Kron, kron
+
+try:
+    import scipy.linalg
+    imported_scipy = True
+except ImportError:
+    imported_scipy = False
+
+
+class TestKron(utt.InferShapeTester):
+
+    rng = numpy.random.RandomState(43)
+
+    def setUp(self):
+        super(TestKron, self).setUp()
+        self.op_class = Kron
+        self.op = kron
+
+    def test_perform(self):
+        assert imported_scipy, (
+            "Scipy not available. Scipy is needed for TestKron")
+        x = tensor.dmatrix()
+        y = tensor.dmatrix()
+        f = function([x, y], kron(x, y))
+
+        for shp0 in [(8, 6), (5, 8)]:
+            for shp1 in [(5, 7), (3, 3)]:
+                a = numpy.random.rand(*shp0)
+                b = numpy.random.rand(*shp1)
+                out = f(a, b)
+                assert numpy.allclose(out, scipy.linalg.kron(a, b))
+
+    def test_infer_shape(self):
+        x = tensor.dmatrix()
+        y = tensor.dmatrix()
+        self._compile_and_check([x, y], [self.op(x, y)],
+                                [numpy.random.rand(8, 5),
+                                 numpy.random.rand(3, 7)],
+                                self.op_class)
+        self._compile_and_check([x, y], [self.op(x, y)],
+                                [numpy.random.rand(2, 5),
+                                 numpy.random.rand(6, 3)],
+                                self.op_class)
+
+if __name__ == "__main__":
+    t = TestKron('setUp')
+    t.setUp()
+    t.test_perform()
+    t.test_infer_shape()