Merge pull request #2404 from pllim/range-cen

Add center and move_to methods to RangeSubsetState

glue/core/subset.py

@@ -809,6 +809,14 @@ def to_mask(self, data, view=None):
         result = (x >= self.lo) & (x <= self.hi)
         return result
 
+    def center(self):
+        return (self.hi - self.lo) * 0.5 + self.lo
+
+    def move_to(self, new_cen):
+        dx = new_cen - self.center()
+        self.lo = self.lo + dx
+        self.hi = self.hi + dx
+
     def copy(self):
         return RangeSubsetState(self.lo, self.hi, self.att)
 

glue/core/tests/test_subset.py

@@ -828,12 +828,18 @@ def test_range_subset_state(self):
 
         subset = self.data.new_subset()
         subset.subset_state = RangeSubsetState(1.1, 1.4, self.data.id['c'])
+        assert_allclose(subset.subset_state.center(), 1.25)
         assert_equal(self.data.subsets[0].to_mask(), [1, 1, 0, 0])
 
         data_clone = clone(self.data)
 
         assert_equal(data_clone.subsets[0].to_mask(), [1, 1, 0, 0])
 
+        # Also test moving it.
+        subset.subset_state.move_to(2)
+        assert_allclose((subset.subset_state.lo, subset.subset_state.hi), (1.85, 2.15))
+        assert_allclose(subset.subset_state.center(), 2)
+
     def test_and_subset_state(self):
 
         subset = self.data.new_subset()