Python:初始化空嵌套列表时的奇怪列表行为
有人能解释一下原因吗:Python:初始化空嵌套列表时的奇怪列表行为,python,python-3.x,list,Python,Python 3.x,List,有人能解释一下原因吗: b = 10*[[]] b[0].append(3) b现在是: [[3], [3], [3], [3], [3], [3], [3], [3], [3], [3]] 但如果我这样做: b = [[] for _ in range(10)] b[0].append(3) b现在是: [[3], [], [], [], [], [], [], [], [], []] 还要注意 10*[[]] == [[] for [] in range(10)] 返回 True
b = 10*[[]]
b[0].append(3)
b现在是:
[[3], [3], [3], [3], [3], [3], [3], [3], [3], [3]]
但如果我这样做:
b = [[] for _ in range(10)]
b[0].append(3)
b现在是:
[[3], [], [], [], [], [], [], [], [], []]
还要注意
10*[[]] == [[] for [] in range(10)]
返回
True
(在Python 3.6.1中测试)
because:
>>> b = 10*[[]]
>>> b[0] is b[1]
True
>>> b = [[] for _ in range(10)]
>>> b[0] is b[1]
False
>>>