Python cookbook(数据结构与算法)从序列中移除重复项且保持元素间顺序不变的方法

# example.py
#
# Remove duplicate entries from a sequence while keeping order
def dedupe(items):
  seen = set()
  for item in items:
    if item not in seen:
      yield item
      seen.add(item)
if __name__ == '__main__':
  a = [1, 5, 2, 1, 9, 1, 5, 10]
  print(a)
  print(list(dedupe(a)))

[1, 5, 2, 1, 9, 1, 5, 10]
[1, 5, 2, 9, 10]

# example2.py
#
# Remove duplicate entries from a sequence while keeping order
def dedupe(items, key=None):
  seen = set()
  for item in items:
    val = item if key is None else key(item)
    if val not in seen:
      yield item
      seen.add(val)
if __name__ == '__main__':
  a = [ 
    {'x': 2, 'y': 3},
    {'x': 1, 'y': 4},
    {'x': 2, 'y': 3},
    {'x': 2, 'y': 3},
    {'x': 10, 'y': 15}
    ]
  print(a)
  print(list(dedupe(a, key=lambda a: (a['x'],a['y']))))

[{'x': 2, 'y': 3}, {'x': 1, 'y': 4}, {'x': 2, 'y': 3}, {'x': 2, 'y': 3}, {'x': 10, 'y': 15}]
[{'x': 2, 'y': 3}, {'x': 1, 'y': 4}, {'x': 10, 'y': 15}]