ADD: Adding new gatefilter method to remove last gates.

pyart/filters/gatefilter.py

@@ -695,6 +695,15 @@ def exclude_invalid(self, field, exclude_masked=True, op="or"):
         marked = ~np.isfinite(self._get_fdata(field))
         return self._merge(marked, op, exclude_masked)
 
+    def exclude_last_gates(self, field, n_gates=10, exclude_masked=True, op="or"):
+        """
+        Excludes a number of gates at the end of each ray. This is useful
+        for when trying to exclude "ring artifacts" in some datasets.
+        """
+        marked = np.full(self._get_fdata(field).shape, False)
+        marked[:, -n_gates:] = True
+        return self._merge(marked, op, exclude_masked)
+
     def exclude_gates(self, mask, exclude_masked=True, op="or"):
         """
         Exclude gates where a given mask is equal True.

tests/filters/test_gatefilter.py

@@ -239,6 +239,20 @@ def test_gatefilter_ops():
     assert gfilter.gate_excluded[0, 9] is np.True_
 
 
+def test_gatefilter_exclude_last_gates():
+    gfilter = pyart.correct.GateFilter(radar)
+    gfilter.exclude_last_gates("test_field", n_gates=2)
+    assert gfilter.gate_excluded[0, 0] is np.False_
+    assert gfilter.gate_excluded[0, 8] is np.True_
+    assert gfilter.gate_excluded[0, 9] is np.True_
+
+    gfilter = pyart.correct.GateFilter(radar)
+    gfilter.exclude_last_gates("test_field", n_gates=1)
+    assert gfilter.gate_excluded[0, 0] is np.False_
+    assert gfilter.gate_excluded[0, 8] is np.False_
+    assert gfilter.gate_excluded[0, 9] is np.True_
+
+
 def test_gatefilter_raises():
     gfilter = pyart.correct.GateFilter(radar)
     pytest.raises(ValueError, gfilter.exclude_below, "test_field", 0.5, op="fuzz")