43 lines
1.6 KiB
Markdown
43 lines
1.6 KiB
Markdown
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---
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title: Python All Iterable
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localeTitle: Python所有Iterable
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---
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`all()`是Python 3中的内置函数（以及2.5版以来的Python 2），用于检查[_iterable的_](https://docs.python.org/3/glossary.html#term-iterable)所有项是否为`True` 。它需要一个参数， `iterable` 。
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## 论据
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### 迭代
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`iterable`参数是要检查其条目的集合。它可以是`list` ， `str` ， `dict` ， `tuple`等。
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## 回报价值
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返回值是一个布尔值。当且仅当`iterable` **所有**条目都是[真实的时](https://guide.freecodecamp.org/python/truth-value-testing) ，它返回`True` 。该函数基本上对所有元素执行布尔`AND`运算。
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如果它们中的一个不是真的，则返回`False` 。
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`all()`操作等效于（不是内部实现完全像这样）
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```
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def all(iterable):
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for element in iterable:
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if not element:
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return False
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return True
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```
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## 代码示例
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```
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print(all([])) #=> True # Because an empty iterable has no non-truthy elements
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print(all([6, 7])) #=> True
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print(all([6, 7, None])) #=> False # Because it has None
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print(all([0, 6, 7])) #=> False # Because it has zero
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print(all([9, 8, [1, 2]])) #=> True
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print(all([9, 8, []])) #=> False # Because it has []
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print(all([9, 8, [1, 2, []]])) #=> True
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print(all([9, 8, {}])) #=> False # Because it has {}
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print(all([9, 8, {'engine': 'Gcloud'}])) #=> True
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```
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 [运行代码](https://repl.it/CL9U/0)
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[官方文件](https://docs.python.org/3/library/functions.html#all)
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