Python frozenset集合的实现

# 从列表创建
fs1 = frozenset([1, 2, 3, 4, 5])
print(fs1)  # 输出: frozenset({1, 2, 3, 4, 5})

# 从元组创建
fs2 = frozenset((1, 2, 3))
print(fs2)  # 输出: frozenset({1, 2, 3})

# 从字符串创建
fs3 = frozenset('hello')
print(fs3)  # 输出: frozenset({'h', 'e', 'l', 'o'})

# 创建空frozenset
fs4 = frozenset()
print(fs4)  # 输出: frozenset()

# 从set创建
regular_set = {1, 2, 3}
fs = frozenset(regular_set)
print(fs)  # 输出: frozenset({1, 2, 3})

# 从字典创建（只使用键）
dict_keys = frozenset({'a': 1, 'b': 2}.keys())
print(dict_keys)  # 输出: frozenset({'a', 'b'})

# 创建两个frozenset
fs1 = frozenset([1, 2, 3, 4])
fs2 = frozenset([3, 4, 5, 6])

# 计算交集
intersection = fs1 & fs2
print(f"交集: {intersection}")  # 输出: frozenset({3, 4})

# 计算并集
union = fs1 | fs2
print(f"并集: {union}")  # 输出: frozenset({1, 2, 3, 4, 5, 6})

# 计算差集
difference = fs1 - fs2
print(f"差集: {difference}")  # 输出: frozenset({1, 2})

# 计算对称差集
symmetric_diff = fs1 ^ fs2
print(f"对称差集: {symmetric_diff}")  # 输出: frozenset({1, 2, 5, 6})

# 检查元素是否存在
print(1 in fs1)  # 输出: True
print(5 in fs1)  # 输出: False

# 获取元素个数
print(len(fs1))  # 输出: 4

fs = frozenset([1, 2, 3])

try:
    fs.add(4)  # 错误：frozenset没有add方法
except AttributeError as e:
    print(f"错误：{e}")

try:
    fs.remove(1)  # 错误：frozenset没有remove方法
except AttributeError as e:
    print(f"错误：{e}")

try:
    fs.clear()  # 错误：frozenset没有clear方法
except AttributeError as e:
    print(f"错误：{e}")

# 使用frozenset作为字典键来存储组合
def store_combinations():
    combinations = {}
    # 存储不同组合的得分
    combinations[frozenset(['apple', 'orange'])] = 85
    combinations[frozenset(['banana', 'grape'])] = 92
    combinations[frozenset(['apple', 'banana'])] = 78
    
    return combinations

# 使用示例
combinations = store_combinations()
# 查找特定组合的得分
search_combination = frozenset(['apple', 'orange'])
print(f"组合 {search_combination} 的得分: {combinations[search_combination]}")

class DataProcessor:
    def __init__(self):
        self.cache = {}
    
    def process_data(self, data_set):
        # 将输入转换为frozenset以用作缓存键
        frozen_data = frozenset(data_set)
        
        # 检查缓存中是否已有结果
        if frozen_data in self.cache:
            print("从缓存中获取结果")
            return self.cache[frozen_data]
        
        # 计算新结果
        print("计算新结果")
        result = sum(frozen_data)  # 示例计算
        self.cache[frozen_data] = result
        return result

# 使用示例
processor = DataProcessor()
print(processor.process_data([1, 2, 3]))  # 计算新结果
print(processor.process_data([3, 2, 1]))  # 从缓存中获取结果（因为集合元素相同）

class Configuration:
    def __init__(self, settings):
        self._settings = frozenset(settings)
    
    @property
    def settings(self):
        return self._settings
    
    def has_setting(self, setting):
        return setting in self._settings
    
    def is_compatible_with(self, other_config):
        return bool(self._settings & other_config.settings)

# 使用示例
config1 = Configuration(['debug', 'logging', 'cache'])
config2 = Configuration(['logging', 'security', 'api'])

print(f"Config1设置: {config1.settings}")
print(f"是否启用debug: {config1.has_setting('debug')}")
print(f"配置是否兼容: {config1.is_compatible_with(config2)}")

import sys

# 比较set和frozenset的内存使用
data = list(range(1000))
regular_set = set(data)
frozen_set = frozenset(data)

print(f"set内存使用: {sys.getsizeof(regular_set)} bytes")
print(f"frozenset内存使用: {sys.getsizeof(frozen_set)} bytes")

import timeit

# 比较set和frozenset的创建性能
set_creation = timeit.timeit('set(range(100))', number=10000)
frozenset_creation = timeit.timeit('frozenset(range(100))', number=10000)

print(f"set创建时间: {set_creation:.6f}秒")
print(f"frozenset创建时间: {frozenset_creation:.6f}秒")

# 好的实践：直接创建frozenset
fs = frozenset([1, 2, 3])

# 避免：先创建set再转换
s = set([1, 2, 3])
fs = frozenset(s)  # 额外的转换步骤

def safe_create_frozenset(data):
    try:
        return frozenset(data)
    except TypeError as e:
        print(f"错误：输入数据不可哈希 - {e}")
        return frozenset()  # 返回空frozenset

# 使用示例
valid_data = [1, 2, 3]
invalid_data = [1, [2, 3], 4]  # 包含列表，不可哈希

print(safe_create_frozenset(valid_data))
print(safe_create_frozenset(invalid_data))

# frozenset的相等性比较基于其元素
fs1 = frozenset([1, 2, 3])
fs2 = frozenset([3, 2, 1])
print(fs1 == fs2)  # 输出: True

# frozenset可以计算哈希值
fs = frozenset([1, 2, 3])
print(f"哈希值: {hash(fs)}")