Add removeAndClearMaskPlane function to MultibandMask

This function was missing in the MultibandMask class.  A unittest
was also added.

python/lsst/afw/image/image/multiband.py

@@ -489,6 +489,27 @@ def removeMaskPlane(name):
         """
         Mask[MaskPixel].removeMaskPlane(name)
 
+    def removeAndClearMaskPlane(self, name, removeFromDefault=False):
+        """Remove and clear a mask from the mask plane
+
+        Clear all pixels of the specified mask and remove the plane from the
+        mask plane dictionary.  Also optionally remove the plane from the
+        default dictionary.
+
+        Parameters
+        ----------
+        name : `str`
+           Name of the mask plane to remove
+        removeFromDefault : `bool`, optional
+           Whether to remove the mask plane from the default dictionary.
+           Default is `False`.
+        """
+        # Clear all masks in MultibandMask but leave in default dict for now
+        for single in self.singles:
+            single.removeAndClearMaskPlane(name, removeFromDefault=False)
+        # Now remove from default dict according to removeFromDefault
+        self._refMask.removeAndClearMaskPlane(name, removeFromDefault)
+
     def clearAllMaskPlanes(self):
         """Clear all the pixels
         """

tests/test_multiband.py

@@ -339,6 +339,28 @@ def testRemoveMaskPlane(self):
         self.assertIn("FOO", mMask.getMaskPlaneDict())
         self.assertNotIn("FOO", Mask().getMaskPlaneDict())
 
+    def testRemoveAndClearMaskPlane(self):
+        mMask = self.mMask1
+        # Add mask plane FOO and test clearing it without removing plane from
+        # default dict
+        mMask.addMaskPlane("FOO")
+        mMask.removeAndClearMaskPlane("FOO")
+        self.assertNotIn("FOO", mMask.getMaskPlaneDict())
+        self.assertIn("FOO", Mask().getMaskPlaneDict())
+        # Now also remove it from default dict
+        mMask.addMaskPlane("FOO")
+        mMask.removeAndClearMaskPlane("FOO", removeFromDefault=True)
+        self.assertNotIn("FOO", mMask.getMaskPlaneDict())
+        self.assertNotIn("FOO", Mask().getMaskPlaneDict())
+        # Now remove and clear the EDGE mask plane and make sure all of the planes
+        # in the MultibandMask (i.e. the "singles") got updated accordingly
+        mMask.removeAndClearMaskPlane("EDGE", removeFromDefault=True)
+        self.assertNotIn("EDGE", mMask.getMaskPlaneDict())
+        self.assertNotIn("EDGE", Mask().getMaskPlaneDict())
+        # Assert that all mask planes were updated (i.e. having EDGE removed)
+        self.assertTrue(np.all([s.array == self.values1[n] & ~self.EDGE for
+                                n, s in enumerate(mMask.singles)]))
+
     def testFilterSlicing(self):
         _testImageFilterSlicing(self, self.mMask1, Mask, self.bbox, self.values1[0])