Add dtype option to identity_like

Resolves #816

aesara/tensor/basic.py

@@ -1422,8 +1422,22 @@ def eye(n, m=None, k=0, dtype=None):
     return localop(n, m, k)
 
 
-def identity_like(x):
-    return eye(x.shape[0], x.shape[1], k=0, dtype=x.dtype)
+def identity_like(x, dtype: Optional[Union[str, np.generic, np.dtype]] = None):
+    """Create a tensor with ones on main diagonal and zeroes elsewhere.
+
+    Parameters
+    ----------
+    x : tensor
+    dtype : data-type, optional
+
+    Returns
+    -------
+    tensor
+        tensor the shape of x with ones on main diagonal and zeroes elsewhere of type of dtype.
+    """
+    if dtype is None:
+        dtype = x.dtype
+    return eye(x.shape[0], x.shape[1], k=0, dtype=dtype)
 
 
 def infer_broadcastable(shape):

doc/library/tensor/basic.rst

@@ -777,12 +777,13 @@ Creating Tensors
     :returns: An array where all elements are equal to zero, except for the `k`-th
               diagonal, whose values are equal to one.
 
-.. function:: identity_like(x)
+.. function:: identity_like(x, dtype=None)
 
     :param x: tensor
+    :param dtype: The dtype of the returned tensor. If `None`, default to dtype of `x`
     :returns: A tensor of same shape as `x` that is filled with zeros everywhere
               except for the main diagonal, whose values are equal to one. The output
-              will have same dtype as `x`.
+              will have same dtype as `x` unless overridden in `dtype`.
 
 .. function:: stack(tensors, axis=0)
 

tests/tensor/test_basic.py

@@ -59,6 +59,7 @@
     get_scalar_constant_value,
     get_vector_length,
     horizontal_stack,
+    identity_like,
     infer_broadcastable,
     inverse_permutation,
     join,
@@ -4392,6 +4393,15 @@ def test_empty():
     assert res.dtype == "int64"
 
 
+def test_identity_like_dtype():
+    # Test that we allocate eye correctly via identity_like
+    m = matrix(dtype="int64")
+    m_out = identity_like(m)
+    assert m_out.dtype == m.dtype
+    m_out_float = identity_like(m, dtype=np.float64)
+    assert m_out_float.dtype == "float64"
+
+
 def test_atleast_Nd():
     ary1 = dscalar()
     res_ary1 = atleast_Nd(ary1, n=1)