Merge pull request nipreps#50 from celprov/enh/averagedw-model

ENH: Add regression to the mean model

eddymotion/model.py

@@ -98,6 +98,24 @@ def predict(self, gradient, **kwargs):
         return self._S0
 
 
+class AverageDWModel:
+    """A trivial model that returns an average map."""
+
+    __slots__ = ("_data", "_gtab")
+
+    def __init__(self, gtab, **kwargs):
+        """Implement object initialization."""
+        self._gtab = gtab
+
+    def fit(self, data, **kwargs):
+        """Calculate the average."""
+        self._data = data[..., self._gtab[..., 3] > 50].mean(-1)
+
+    def predict(self, gradient, **kwargs):
+        """Return the average map."""
+        return self._data
+
+
 class DTIModel:
     """A wrapper of :obj:`dipy.reconst.dti.TensorModel."""