Add matrix_of_scalars function

theano/tensor/basic.py

@@ -8224,3 +8224,19 @@ def diag(v, k=0):
         return diagonal(v, k)
     else:
         raise ValueError("Input must be 1- or 2-d.")
+
+def matrix_of_scalars(list_of_lists):
+    """ Returns a matrix of scalars
+
+    >>> from theano.tensor import matrix_of_scalars, scalar
+    >>> from theano import function
+    >>> a,b,c,d = map(scalar, 'abcd')
+    >>> X = matrix_of_scalars([[a, b],
+    ...                        [c, d]])
+    >>> f = function([a, b, c, d], X)
+    >>> f(1, 2, 3, 4)
+    array([[ 1.,  2.],
+           [ 3.,  4.]], dtype=float32)
+    """
+    from functools import partial
+    return stack(*map(partial(apply, stack), list_of_lists))

theano/tensor/tests/test_basic.py

@@ -43,7 +43,8 @@ from theano.tensor import (_shared, wvector, bvector, autocast_float_as,
         ScalarFromTensor, TensorFromScalar, dtensor4, Rebroadcast, Alloc,
         dtensor3, SpecifyShape, Mean, IncSubtensor, AdvancedIncSubtensor1,
         itensor3, Tile, AdvancedIncSubtensor, switch, Diagonal, Diag,
-        nonzero, flatnonzero, nonzero_values, inplace_increment)
+        nonzero, flatnonzero, nonzero_values, inplace_increment,
+        matrix_of_scalars)
 from theano.tests import unittest_tools as utt
 
 
@@ -6778,6 +6779,15 @@ def test_transpose():
     assert tensor.transpose(x3).name == 'x3.T'
     assert tensor.transpose(tensor.dmatrix()).name is None
 
+def test_matrix_of_scalars():
+    a,b,c,d = map(scalar, 'abcd')
+    X = matrix_of_scalars([[a, b],
+                           [c, d]])
+    f = function([a, b, c, d], X)
+    result = f(1,2,3,4)
+    assert result.shape == (2, 2)
+    assert numpy.allclose(f(1, 2, 3, 4), numpy.asarray([[1,2],[3,4]]))
+
 
 class TestSpecifyShape(unittest.TestCase):
     def shortDescription(self):