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45 lines
1.5 KiB
Markdown
45 lines
1.5 KiB
Markdown
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## **ucollections** – 集合与容器类型
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**ucollections** 模块实现了专门的容器数据类型，它提供了 Python 的通用内置容器的替代方案，包括了字典、列表、集合和元组。
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### 类
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#### **ucollections.namedtuple**(name, fields)
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这是工厂函数创建一个新的 `namedtuple` 型与一个特定的字段名称和集合。`namedtuple` 是元组允许子类要访问它的字段不仅是数字索引，而且还具有属性使用符号字段名访问语法。 字段是字符串序列指定字段名称。为了兼容的实现也可以用空间分隔的字符串命名的字段（但效率较低） 。
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代码示例：
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```python
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from ucollections import namedtuple
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MyTuple = namedtuple("MyTuple", ("id", "name"))
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t1 = MyTuple(1, "foo")
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t2 = MyTuple(2, "bar")
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print(t1.name)
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assert t2.name == t2[1]
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ucollections.OrderedDict(...)
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```
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#### **ucollections.OrderedDict**(...)
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字典类型的子类，会记住并保留键/值的追加顺序。当有序的字典被迭代输出时，键/值 会按照他们被添加的顺序返回 :
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```python
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from ucollections import OrderedDict
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# To make benefit of ordered keys, OrderedDict should be initialized
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# from sequence of (key, value) pairs.
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d = OrderedDict([("z", 1), ("a", 2)])
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# More items can be added as usual
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d["w"] = 5
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d["b"] = 3
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for k, v in d.items():
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print(k, v)
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```
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输出:
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z 1
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a 2
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w 5
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b 3
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更多的内容可参考 [ucollections](http://docs.micropython.org/en/latest/pyboard/library/ucollections.html) 。
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