根據對象列表創建整數元素列表

Question

我需要從對象列表創建非重複整數元素列表。

例如： 有兩個屬性的對象：「身份證」和「other_id」：

first = [elem.id for elem in objects_list] 
second = [elem.other_id for elem in objects_list] 
print first 
[0,1,2,3,4,5] 
print second 
[4,5,6,7,9] 

現在我可以創建一個包含兩個列表，從所有對象的兩個屬性是這樣的：

first = [elem.id for elem in objects_list] 
first.extend(elem.other_id for elem in objects_list if elem.other_id not in first) 
print first 
[0,1,2,3,4,5,6,7,9] 

有什麼辦法可以做到這一點嗎？

Answer 1

使用set：

sorted(set().union(first, second)) #returns a sorted list of unique items 

演示：

>>> first = [0,1,2,3,4,5] 
>>> second = [4,5,6,7,9] 
>>> sorted(set(first + second)) 
[0, 1, 2, 3, 4, 5, 6, 7, 9] 

如果原來的順序事項：

>>> first = [0,1,2,3,4,5] 
>>> seen = set(first) 
>>> first += [x for x in second if x not in seen and not seen.add(x)] 
>>> first 
[0, 1, 2, 3, 4, 5, 6, 7, 9] 

對於大名單的設置方法將是有效的作爲集提供O(1)查找，對於小列表，你的方法也沒關係。