升木 发表于 2018-8-15 09:05:00

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']
  转至:http://blog.csdn.net/zhengnz/article/details/6265282
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