added gmi measure

Author: maniospas

fairbench/v2/blocks/measures/classification.py

@@ -257,3 +257,32 @@ def f1(predictions, labels, sensitive=None):
             quantities.an(n),
         ],
     )
+
+
+
+@c.measure("the geometric mean of tpr and tnr - accounts for class imbalance")
+def gmi(predictions, labels, sensitive=None):
+    predictions = np.array(predictions)
+    labels = np.array(labels)
+    sensitive = np.ones_like(predictions) if sensitive is None else np.array(sensitive)
+
+    tp = (predictions * sensitive * labels).sum()
+    tn = ((1 - predictions) * sensitive * (1 - labels)).sum()
+    p = (labels * sensitive).sum()
+    n = ((1 - labels) * sensitive).sum()
+    fn = p - tp
+    fp = n - tn
+
+    precision = 0 if (tp + fp) == 0 else tp / (tp + fp)
+    recall = 0 if (tp + fn) == 0 else tp / (tp + fn)
+    value = precision*recall
+
+    return c.Value(
+        c.TargetedNumber(value, 1),
+        depends=[
+            quantities.tp(tp),
+            quantities.tn(tn),
+            quantities.ap(p),
+            quantities.an(n),
+        ],
+    )

fairbench/v2/core/framework.py

@@ -38,7 +38,7 @@ def wrapper(**kwargs) -> Value:
                 or isinstance(value.value, int)
             ), f"{descriptor} computed {type(value.value)} instead of float, int, Number, or TargetedNumber"
             if unit and 1 < float(value) < 1 + eps:  # take care of rounding errors
-                value = 1.0
+                value.value = 1.0
             assert not unit or (
                 0 <= float(value) <= 1
             ), f"{descriptor} computed {float(value)} that is not in [0,1]"

fairbench/v2/core/values.py

@@ -337,7 +337,9 @@ def exists(self) -> bool:
                 return True
         return False
 
-    def rebase(self, dep: Descriptor):
+    def rebase(self, dep: Descriptor|str):
+        if isinstance(dep,str):
+            dep = Descriptor(dep, self.descriptor.role)
         return Value(self.value, dep, list(self.depends.values()))
 
     def tostring(self, tab="", depth=0, details: bool = False):

fairbench/v2/reports/adhoc.py

@@ -12,6 +12,7 @@
     blocks.measures.tnr,
     blocks.measures.ppv,
     blocks.measures.f1,
+    blocks.measures.gmi,
     blocks.measures.tar,
     blocks.measures.trr,
     blocks.measures.lift,