Add "merge" method into IntervalSet class.

pyinter/interval_set.py

@@ -130,3 +130,24 @@ def difference(self, other):
     def complement(self):
         intersection = lambda a, b: a.intersection(b)
         return functools.reduce(intersection, [interval.complement() for interval in list(self)])
+
+    def merge(self):
+        """
+        Merge overlapping intervals
+        For example, {(0,3), (3,6), (5,10]} => {(0,3), (3,10]}
+        """
+        result = IntervalSet()
+        if self.empty():
+            return result
+        sorted_intervals = sorted(self._data)
+        now = sorted_intervals[0]
+        for interval in sorted_intervals[1:]:
+            if now.upper_value<interval.lower_value or \
+                    (now.upper_value==interval.lower_value and now.upper==0 and interval.lower==0):
+                result._data.add(now.copy())
+                now = interval
+            else:
+                now.upper_value = interval.upper_value
+                now.upper = interval.upper
+        result._data.add(now.copy())
+        return result

tests/test_interval_set.py

@@ -261,3 +261,7 @@ def test_repr():
 def test_comparison_raises_not_implemented_error_if_it_cannot_compare():
     with pytest.raises(NotImplementedError):
         IntervalSet() == 1
+
+def test_merge():
+    interval_set = IntervalSet([i.open(0, 3), i.open(3, 6), i.closed(5, 10)])
+    assert repr(interval_set) == 'IntervalSet((0, 3), (3, 10])'