python 使用小技巧，持續更新。。。
阿新 • • 發佈：2019-01-22
python list去重
（參看：https://www.cnblogs.com/infim/archive/2011/03/10/1979615.html）
前後順序改變：
l1 = ['b','c','d','b','c','a','a']
l2 = list(set(l1))
print l2
l1 = ['b','c','d','b','c','a','a']
l2 = {}.fromkeys(l1).keys()
print l2
result:['a', 'c', 'b', 'd']
保持順序不變：
l1 = ['b','c','d','b','c','a','a']
l2 = list(set(l1))
l2.sort(key=l1.index)
print l2
l1 = ['b','c','d','b','c','a','a']
l2 = sorted(set(l1),key=l1.index)
print l2
l1 = ['b','c','d','b','c','a','a']
l2 = []
[l2.append(i) for i in l1 ifnot i in l2]
print l2
result：['b', 'c', 'd', 'a']