40 lines
1.7 KiB
Markdown
40 lines
1.7 KiB
Markdown
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---
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title: Python Frozenset
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---
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**`frozenset` basic info**<br>
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The `frozenset` type is a builtin set types which is immutable and hashable -- its contents cannot be altered after it is created; however, it can be used as a dictionary key or as an element of another set. Frozensets are like sets except that they cannot be changed, i.e they are immutale.
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>>> cities = frozenset(["Frankfurt", "Basel", "Freiburg"])
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>>> cities.add("Strasbourg")
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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AttributeError: 'frozenset' object has no attribute 'add'
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>>>
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`frozenset` constructor:<br>
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`frozenset([iterable])` <br>
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The iterable contains elements to initialize the frozenset with. The iterable can be set, dictionary, tuple etc. If no parameter is passed, the `frozenset()` method returns an empty frozenset.
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**Examples** <br>
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>>> vowels = ('a', 'e', 'i', 'o', 'u')
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>>> fSet = frozenset(vowels)
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>>> print("The frozen set is: ", fSet)
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The frozen set is: frozenset({'i', 'e', 'a', 'u', 'o'})
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>>> print("The empty frozen set is: ", frozenset())
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The empty frozen set is: frozenset()
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>>>
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**Another Example** <br>
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>>> person = {"name": "John", "age": 23, "sex": "male"}
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>>> fSet = frozenset(person)
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>>> print("The frozen set is: ", fSet)
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The frozen set is: frozenset({'sex', 'name', 'age'})
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>>>
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**Additional Information** <br>
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<a href="https://www.programiz.com/python-programming/methods/built-in/frozenset">Python Frozenset()</a> <br>
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<a href="https://docs.python.org/2.4/lib/types-set.html">Set Types -- set, frozenset</a> <br>
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<a href="https://www.python-course.eu/sets_frozensets.php">Python Tutorial: Sets and Frozen sets</a>
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