Add product function extension

imagewect/wect.py

@@ -72,30 +72,7 @@ def __get_maxfe_weight(s, weights):
     if d == 1:
         return max([weights[s[0]], weights[s[1]]])
     return max([weights[s[0]], weights[s[1]], weights[s[2]]])
-
-def __get_simplex_weight(s, weights, fe):
-    """
-    Computes the weight of a simplex based on the function extension specified.
 
-    Args:
-        s (dionysus.Simplex): The simplex.
-        weights (np.ndarray): The weights array.
-        fe (str): The function extension to use for computing weights.
-
-    Returns:
-        float: The weight of the simplex.
-    """
-    if fe == "MAX":
-        return __get_maxfe_weight(s, weights)
-    elif fe == "MIN":
-        return __get_minfe_weight(s, weights)
-    elif fe == "AVG":
-        return __get_avgfe_weight(s, weights)
-    elif fe == "EC":
-        return 1
-    else:
-        raise NotImplementedError(f"unknown function extension \"{fe}\"")
-
 
 def __get_minfe_weight(s, weights):
     """
@@ -143,6 +120,56 @@ def __get_avgfe_weight(s, weights):
         return sum([weights[s[0]], weights[s[1]], weights[s[2]]]) / 3
 
 
+def __get_productfe_weight(s, weights):
+    """
+    Computes the weight of a simplex using the Product function extension.
+    (i.e. the simplex weight is the product of the weight of each 0-dimensional component of the simplex)
+
+    Args:
+        s (dionysus.Simplex): The simplex.
+        weights (np.ndarray): The weights array.
+
+    Returns:
+        float: The weight of the simplex under the product extension.
+    """
+    if __contains_zero_weights(s, weights):
+        return 0
+
+    d = s.dimension()
+    if d == 0:
+        return weights[s[0]]
+    elif d == 1:
+        return weights[s[0]] * weights[s[1]]
+    else:
+        return weights[s[0]] * weights[s[1]] * weights[s[2]]
+
+
+def __get_simplex_weight(s, weights, fe):
+    """
+    Computes the weight of a simplex based on the function extension specified.
+
+    Args:
+        s (dionysus.Simplex): The simplex.
+        weights (np.ndarray): The weights array.
+        fe (str): The function extension to use for computing weights.
+
+    Returns:
+        float: The weight of the simplex.
+    """
+    if fe == "MAX":
+        return __get_maxfe_weight(s, weights)
+    elif fe == "MIN":
+        return __get_minfe_weight(s, weights)
+    elif fe == "AVG":
+        return __get_avgfe_weight(s, weights)
+    elif fe == "PRODUCT":
+        return __get_productfe_weight(s, weights)
+    elif fe == "EC":
+        return 1
+    else:
+        raise NotImplementedError(f"unknown function extension \"{fe}\"")
+
+
 def vectorize_wect(wect, height_vals):
     """
     Vectorizes the WECT by computing its values at specified height values.