Merge pull request #278 from larrybradley/mask-fix

Fix corner-case issue in RegionMask.multiply()

CHANGES.rst

@@ -7,6 +7,13 @@ New Features
 - Added ``union`` and ``intersection`` methods to the ``BoundingBox``
   class. [#277]
 
+Bug Fixes
+---------
+
+- Fixed a corner-case issue where ``RegionMask.multiply()`` would not set
+  non-finite data values outside of the mask but within the bounding box
+  to zero. [#278]
+
 
 0.3 (2018-09-09)
 ================

regions/core/mask.py

@@ -36,6 +36,7 @@ def __init__(self, data, bbox):
             raise ValueError('data and bounding box must have the same '
                              'shape.')
         self.bbox = bbox
+        self._mask = (self.data == 0)
 
     def __array__(self):
         """
@@ -158,8 +159,8 @@ def cutout(self, data, fill_value=0., copy=False):
             A 2D array on which to apply the region mask.
 
         fill_value : float, optional
-            The value is used to fill pixels where the region mask
-            does not overlap with the input ``data``.  The default is 0.
+            The value used to fill pixels where the region mask does not
+            overlap with the input ``data``.  The default is 0.
 
         copy : bool, optional
             If `True` then the returned cutout array will always be hold
@@ -245,4 +246,10 @@ def multiply(self, data, fill_value=0.):
         if cutout is None:
             return None
         else:
-            return cutout * self.data
+            weighted_cutout = cutout * self.data
+
+            # needed to zero out non-finite data values outside of the
+            # mask but within the bounding box
+            weighted_cutout[self._mask] = 0.0
+
+            return weighted_cutout

regions/core/tests/test_mask.py

@@ -90,3 +90,27 @@ def test_mask_cutout_partial_overlap(position):
 
     image = mask.to_image(data.shape)
     assert image.shape == data.shape
+
+
+def test_mask_nan_in_bbox():
+    """
+    Regression test that non-finite data values outside of the mask but
+    within the bounding box are set to zero.
+    """
+
+    data = np.ones((101, 101))
+    data[33, 33] = np.nan
+    data[67, 67] = np.inf
+    data[33, 67] = -np.inf
+    data[22, 22] = np.nan
+    data[22, 23] = np.inf
+
+    radius = 20.
+    reg1 = CirclePixelRegion(PixCoord(50, 50), radius)
+    reg2 = CirclePixelRegion(PixCoord(5, 5), radius)
+
+    wdata1 = reg1.to_mask(mode='exact').multiply(data)
+    assert_allclose(np.sum(wdata1), np.pi * radius**2)
+
+    wdata2 = reg2.to_mask(mode='exact').multiply(data)
+    assert_allclose(np.sum(wdata2), 561.6040111923013)