Modify documentation to clarify that empty intervals are allowed.

torch_mutual_information/mutual_information.py

@@ -161,7 +161,8 @@ def mutual_information_recursion(px, py, boundary=None):
                has stride of 1; this is true if px and py are contiguous.
 
           boundary:  If supplied, a torch.LongTensor of shape [B][4], where each row contains
-               [s_begin, t_begin, s_end, t_end].  If not supplied, the values
+               [s_begin, t_begin, s_end, t_end], with 0 <= s_begin <= s_end < S and
+               0 <= t_begin <= t_end < T (this implies that empty sequences are allowed).  If not supplied, the values
                [0, 0, S, T] will be assumed.  These are the beginning and
                one-past-the-last positions in the x and y sequences
                respectively, and can be used if not all sequences are of the same length.

torch_mutual_information/mutual_information_test.py

@@ -15,7 +15,7 @@ def test_mutual_information_basic():
                      random.randint(1, 200))
         random_px = (random.random() < 0.2)
         random_py = (random.random() < 0.2)
-        random_boundary = (random.random() < 0.2)
+        random_boundary = (random.random() < 0.7)
         big_px = (random.random() < 0.2)
         big_py = (random.random() < 0.2)
 
@@ -32,8 +32,8 @@ def test_mutual_information_basic():
                     def get_boundary_row():
                         s_begin = random.randint(0, S - 1)
                         t_begin = random.randint(0, T - 1)
-                        s_end = random.randint(s_begin + 1, S)
-                        t_end = random.randint(t_begin + 1, T)
+                        s_end = random.randint(s_begin, S)  # allow empty sequence
+                        t_end = random.randint(t_begin, T)  # allow empty sequence
                         return [s_begin, t_begin, s_end, t_end]
                     if device == torch.device('cpu'):
                         boundary = torch.tensor([ get_boundary_row() for _ in range(B) ],
@@ -73,7 +73,7 @@ def test_mutual_information_basic():
                 #m = mutual_information_recursion(px, py, None)
                 m = mutual_information_recursion(px, py, boundary)
 
-                #print("m = ", m, ", size = ", m.shape)
+                print("m = ", m, ", size = ", m.shape)
                 #print("exp(m) = ", m.exp())
                 (m.sum() * 3).backward()
                 #print("px_grad = ", px.grad)
@@ -101,7 +101,7 @@ def test_mutual_information_deriv():
                      random.randint(1, 200))
         random_px = (random.random() < 0.2)
         random_py = (random.random() < 0.2)
-        random_boundary = (random.random() < 0.2)
+        random_boundary = (random.random() < 0.7)
         big_px = (random.random() < 0.2)
         big_py = (random.random() < 0.2)