枫叶飞翔 发表于 2015-4-27 10:04:30

Python 去除列表中重复的元素

比较容易记忆的是用内置的set








l1 = ['b','c','d','b','c','a','a']
l2 = list(set(l1))
print l2

还有一种据说速度更快的,没测试过两者的速度差别

l1 = ['b','c','d','b','c','a','a']
l2 = {}.fromkeys(l1).keys()
print l2

这两种都有个缺点,祛除重复元素后排序变了:
['a', 'c', 'b', 'd']



如果想要保持他们原来的排序:

用list类的sort方法
l1 = ['b','c','d','b','c','a','a']
l2 = list(set(l1))
l2.sort(key=l1.index)
print l2
也可以这样写

l1 = ['b','c','d','b','c','a','a']
l2 = sorted(set(l1),key=l1.index)
print l2


也可以用遍历

l1 = ['b','c','d','b','c','a','a']
l2 = []
for i in l1:
    if not i in l2:
      l2.append(i)
print l2
上面的代码也可以这样写

l1 = ['b','c','d','b','c','a','a']
l2 = []

print l2


这样就可以保证排序不变了:
['b', 'c', 'd', 'a']








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