added non negative uniform loss

Alignment-and-Uniformity.py

@@ -19,6 +19,7 @@ Returns:
     "x_unif_loss": float(x_unif_loss_v),
     "y_unif_loss": float(y_unif_loss_v),
     "unif_loss": float(unif_loss)
+    
             
 Examples:
 
@@ -40,9 +41,17 @@ def uniform_loss(x, t=2):
     return torch.pdist(x, p=2).pow(2).mul(-t).exp().mean().log()
 
 
+def nonneg_uniform_loss(x, t=2):
+    tmp = torch.pdist(x, p=2).pow(2)
+    original = tmp.mul(-t).exp().mean().log()
+    boundary = -t * tmp.mean()
+    return original - boundary
+
+
 @evaluate.utils.file_utils.add_start_docstrings(_DESCRIPTION, _KWARGS_DESCRIPTION)
 class AlignmentandUniformity(evaluate.Metric):
-    def __init__(self, align_alpha: float = 2.0, unif_t: float = 2.0, *args, **kwargs):
+    def __init__(self, align_alpha: float = 2.0, unif_t: float = 2.0, 
+                 *args, **kwargs):
         super(AlignmentandUniformity, self).__init__(*args, **kwargs)
         self.align_alpha = align_alpha
         self.unif_t = unif_t
@@ -81,10 +90,17 @@ class AlignmentandUniformity(evaluate.Metric):
         x_unif_loss_v = uniform_loss(xs, t=self.unif_t)
         y_unif_loss_v = uniform_loss(ys, t=self.unif_t)
         unif_loss = (x_unif_loss_v + y_unif_loss_v) / 2
+        
+        nn_x_unif_loss_v = nonneg_uniform_loss(xs, t=self.unif_t)
+        nn_y_unif_loss_v = nonneg_uniform_loss(ys, t=self.unif_t)
+        nn_unif_loss = (nonneg_uniform_loss + nonneg_uniform_loss) / 2
                 
         return {
             "align_loss": float(align_loss_val),
             "x_unif_loss": float(x_unif_loss_v),
             "y_unif_loss": float(y_unif_loss_v),
-            "unif_loss": float(unif_loss)
+            "unif_loss": float(unif_loss),
+            "nonneg_x_unif_loss": float(nn_x_unif_loss_v),
+            "nonneg_y_unif_loss": float(nn_y_unif_loss_v),
+            "nonneg_unif_loss": float(nn_unif_loss)
         }