为什么我可以在 Python 的集合中添加布尔值 False 而不是 True?
问题描述
我刚开始研究 Python 中的 set 数据类型.出于某种原因，每当我将 True 的布尔值添加到集合中时，它都不会出现.但是，如果我将 False 添加到集合中，它将成为集合的元素.当我用谷歌搜索这个问题时，我感到很震惊.
I just started investigating the set data type in Python. For some reason, whenever I add the Boolean value of True to a set it doesn't appear. However, if I add False to a set it will become an element of the set. I was shocked when I googled this question that nothing came up.
example1 = {1, 2, 7, False}
example2 = {7, 2, 4, 1, True}
print(example1)
print(example2)
输出是:
{False, 1, 2, 7}
{1, 2, 4, 7}
解决方案
因为在 Python 中 1 == True (和 hash(1) == hash(True)) 并且您的集合中已经有 1 个.
Because in Python 1 == True (and hash(1) == hash(True)) and you have 1 in your set already.
想象一下这个例子:
example1 = {0, False, None}
example2 = {1, True}
print(example1)
print(example2)
将输出:
{0, None}
{1}
第一组有 0 和 None 因为 0 == False 但 0 != None.使用第二个集合 1 == True 所以 True 不会添加到集合中.
First set has 0 and None because 0 == False but 0 != None. With second set 1 == True so True isn't added to the set.
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