列表理解以在词典列表中查找唯一键值

Question

任何人都知道如何使用列表理解来执行以下代码？我因为if条件而陷入困境，我不知道如何使用列表理解来应用。提前谢谢。

x = [{'key':1},{'key':1},{'key':2}, {'key':2}]
y = []

for e in x:
    if e['key'] not in y:
        y.append(e['key'])

>>>print y
[1,2]

Answer 1

对于此特定条件，您可以使用集合理解：

xs = [{'key':1},{'key':1},{'key':2}, {'key':2}]
y = {x['key'] for x in xs}

print y # {1,2}