动态分桶局部敏感哈希
时间: 2024-01-30 12:12:09 浏览: 116
局部敏感哈希
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动态分桶局部敏感哈希是一种局部敏感哈希算法的变体,它通过动态地将数据分配到不同的桶中来提高查询效率。下面是一个动态分桶局部敏感哈希的示例代码:
```python
import random
class DynamicLSH:
def __init__(self, num_buckets, num_hash_functions):
self.num_buckets = num_buckets
self.num_hash_functions = num_hash_functions
self.buckets = [[] for _ in range(num_buckets)]
self.hash_functions = [self._generate_hash_function() for _ in range(num_hash_functions)]
def _generate_hash_function(self):
a = random.randint(1, self.num_buckets - 1)
b = random.randint(0, self.num_buckets - 1)
return lambda x: (a * x + b) % self.num_buckets
def insert(self, data):
for i in range(self.num_hash_functions):
hash_value = self.hash_functions[i](data)
self.buckets[hash_value].append(data)
def query(self, query_data):
candidate_buckets = set()
for i in range(self.num_hash_functions):
hash_value = self.hash_functions[i](query_data)
candidate_buckets.add(hash_value)
candidates = []
for bucket_id in candidate_buckets:
candidates.extend(self.buckets[bucket_id])
return candidates
# 示例用法
lsh = DynamicLSH(num_buckets=10, num_hash_functions=3)
data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
for d in data:
lsh.insert(d)
query_data = 5
result = lsh.query(query_data)
print("Query result:", result)
```
上述代码中,我们首先定义了一个`DynamicLSH`类,它包含了插入数据和查询数据的方法。在初始化时,我们指定了桶的数量和哈希函数的数量,并生成了相应数量的哈希函数。插入数据时,我们根据每个哈希函数的结果将数据分配到对应的桶中。查询数据时,我们根据查询数据经过哈希函数的结果得到候选桶的集合,然后从候选桶中获取所有的数据作为查询结果。
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