http://blog.livedoor.jp/dankogai/archives/51441112.html
>>> a = "0 1 2 3 4 5 6 7 8 9".split() >>> b = "0 2 4 6 8 10 12 14 16 18".split() >>> print set(a) & set(b) set(['0', '8', '2', '4', '6']) >>> print set(a) | set(b) set(['10', '12', '14', '16', '18', '1', '0', '3', '2', '5', '4', '7', '6', '9', '8'])