python 中 for使用小技巧

1 testDict = {i: i * i for i in xrange(10)}
2 testSet = {i * 2 for i in xrange(10)}
3  
4 print(testSet)
5 print(testDict)
6  
7 #set([0, 2, 4, 6, 8, 10, 12, 14, 16, 18])
8 #{0: 0, 1: 1, 2: 4, 3: 9, 4: 16, 5: 25, 6: 36, 7: 49, 8: 64, 9: 81}