[Predator] Move ``SingleFeatureScore`` to LLM.

appengine/findit/crash/loglinear/feature.py

Index: appengine/findit/crash/loglinear/feature.py
diff --git a/appengine/findit/crash/loglinear/feature.py b/appengine/findit/crash/loglinear/feature.py
index 20cda371f4b9ab7c92d40f972f748ebddb8a1f76..4633c9f1869866e3e76dff39fcf75fdf05609a90 100644
--- a/appengine/findit/crash/loglinear/feature.py
+++ b/appengine/findit/crash/loglinear/feature.py
@@ -138,3 +138,27 @@ class Feature(object):
     information and decide the cuplrit based on all the evidence together.
     """
     raise NotImplementedError()
+
+
+class FeatureFunction(object):
+  """Given an iterable of scalar-valued functions, return an dict function.
+
+  Properties:
+    fs (iterable of functions): A collection of curried functions
+    ``X -> Y -> FeatureValue``. That is, given a particular ``x`` they
+    return a function ``Y -> dict(FeatureValue)``. N.B. each function should
+    have a name property.

[wrengr, 2017/01/25 21:54:27]

I still say it'd be clearer to refer to the ``Feature`` interface rather than
calling it a "function with a name property".

+  """
+  def __init__(self, fs):
+    self._fs = fs
+
+  def __call__(self, x):
+    """Fuction mapping ``X -> Y -> dict(FeatureValue.name to FeatureValue).
+
+    Returns:
+      A function ``X -> Y -> dict(FeatureValue.name to FeatureValue)`` where for 
+      all ``x``, ``y``, and for a feature f in fs, we have
+      ``FeatureFunction(fs)(x)(y)[f.name] == f(x)(y)``.
+    """
+    name_to_fx = {f.name: f(x) for f in self._fs}
+    return lambda y: {name: fx(y) for name, fx in name_to_fx.iteritems()}