=== Set === Set comprehension ----------------- .. code-block:: python >>> a = [1, 2, 5, 6, 6, 6, 7] >>> s = {x for x in a} >>> s set([1, 2, 5, 6, 7]) >>> s = {x for x in a if x > 3} >>> s set([5, 6, 7]) >>> s = {x if x > 3 else -1 for x in a} >>> s set([6, 5, -1, 7]) Uniquify a List --------------- .. code-block:: python >>> a = [1, 2, 2, 2, 3, 4, 5, 5] >>> a [1, 2, 2, 2, 3, 4, 5, 5] >>> ua = list(set(a)) >>> ua [1, 2, 3, 4, 5] Union Two Sets -------------- .. code-block:: python >>> a = set([1, 2, 2, 2, 3]) >>> b = set([5, 5, 6, 6, 7]) >>> a | b set([1, 2, 3, 5, 6, 7]) >>> # or >>> a = [1, 2, 2, 2, 3] >>> b = [5, 5, 6, 6, 7] >>> set(a + b) set([1, 2, 3, 5, 6, 7]) Append Items to a Set --------------------- .. code-block:: python >>> a = set([1, 2, 3, 3, 3]) >>> a.add(5) >>> a set([1, 2, 3, 5]) >>> # or >>> a = set([1, 2, 3, 3, 3]) >>> a |= set([1, 2, 3, 4, 5, 6]) >>> a set([1, 2, 3, 4, 5, 6]) Intersection Two Sets --------------------- .. code-block:: python >>> a = set([1, 2, 2, 2, 3]) >>> b = set([1, 5, 5, 6, 6, 7]) >>> a & b set([1]) Common Items from Sets ---------------------- .. code-block:: python >>> a = [1, 1, 2, 3] >>> b = [1, 3, 5, 5, 6, 6] >>> com = list(set(a) & set(b)) >>> com [1, 3] Contain ------- b contains a .. code-block:: python >>> a = set([1, 2]) >>> b = set([1, 2, 5, 6]) >>> a <= b True a contains b .. code-block:: python >>> a = set([1, 2, 5, 6]) >>> b = set([1, 5, 6]) >>> a >= b True Set Diff -------- .. code-block:: python >>> a = set([1, 2, 3]) >>> b = set([1, 5, 6, 7, 7]) >>> a - b set([2, 3]) Symmetric diff -------------- .. code-block:: python >>> a = set([1,2,3]) >>> b = set([1, 5, 6, 7, 7]) >>> a ^ b set([2, 3, 5, 6, 7])