adii1823
52 lines
1.4 KiB
Python
52 lines
1.4 KiB
Python
# sets.py
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>>> small_primes = set() # empty set
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>>> small_primes.add(2) # adding one element at a time
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>>> small_primes.add(3)
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>>> small_primes.add(5)
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>>> small_primes
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{2, 3, 5}
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>>> small_primes.add(1) # Look what I've done, 1 is not a prime!
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>>> small_primes
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{1, 2, 3, 5}
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>>> small_primes.remove(1) # so let's remove it
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>>> 3 in small_primes # membership test
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True
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>>> 4 in small_primes
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False
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>>> 4 not in small_primes # negated membership test
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True
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>>> small_primes.add(3) # trying to add 3 again
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>>> small_primes
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{2, 3, 5} # no change, duplication is not allowed
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>>> bigger_primes = set([5, 7, 11, 13]) # faster creation
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>>> small_primes | bigger_primes # union operator `|`
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{2, 3, 5, 7, 11, 13}
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>>> small_primes & bigger_primes # intersection operator `&`
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{5}
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>>> small_primes - bigger_primes # difference operator `-`
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{2, 3}
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>>> small_primes = {2, 3, 5, 5, 3}
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>>> small_primes
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{2, 3, 5}
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# frozenset
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>>> small_primes = frozenset([2, 3, 5, 7])
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>>> bigger_primes = frozenset([5, 7, 11])
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>>> small_primes.add(11) # we cannot add to a frozenset
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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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>>> small_primes.remove(2) # neither we can remove
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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 'remove'
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>>> small_primes & bigger_primes # intersect, union, etc. allowed
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frozenset({5, 7})
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