python消除序列的重复值并保持顺序不变的实例

$ python
Python 3.5.2 (default, Nov 23 2017, 16:37:01) 
[GCC 5.4.0 20160609] on linux
Type \"help\", \"copyright\", \"credits\" or \"license\" for more information.
>>> a = [1 , 3, 5, 1, 8, 1, 5]
>>> set(a)
{8, 1, 3, 5}
>>> 

$ python
Python 3.5.2 (default, Nov 23 2017, 16:37:01) 
[GCC 5.4.0 20160609] on linux
Type \"help\", \"copyright\", \"credits\" or \"license\" for more information.
>>> def dupe(items):
... seen = set()
... for item in items:
... if item not in seen:
... yield item
... seen.add(item)
... 
>>> a = [1 , 3, 5, 1, 8, 1, 5]
>>> list(dupe(a))
[1, 3, 5, 8]
>>>

Python 3.5.2 (default, Nov 23 2017, 16:37:01) 
[GCC 5.4.0 20160609] on linux
Type \"help\", \"copyright\", \"credits\" or \"license\" for more information.
>>> def rem(items, key=None):
... seen = set()
... for item in items:
... va = item if key is None else key(item)
... if va not in seen:
... yield item
... seen.add(va)
... 
>>> a = [ {\'x\':1, \'y\':2}, {\'x\':1, \'y\':3}, {\'x\':1, \'y\':2}, {\'x\':2, \'y\':4}]>>> list(rem(a, key=lambda d: (d[\'x\'],d[\'y\'])))
[{\'y\': 2, \'x\': 1}, {\'y\': 3, \'x\': 1}, {\'y\': 4, \'x\': 2}]
>>> list(rem(a, key=lambda d: d[\'x\']))
[{\'y\': 2, \'x\': 1}, {\'y\': 4, \'x\': 2}]

>>>>>> #lambda is an anonymous function:
... fuc = lambda : \'haha\'
>>> print (f())
>>> print (fuc())
haha
>>>