posts: bloom-filter: add construction

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Bruno BELANYI 2024-07-14 17:55:15 +01:00
parent 4abcd27ee7
commit 84ce6ea494

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@ -37,3 +37,28 @@ the _false positive_ rate of membership is quite low.
I won't be going into those calculations here, but they are quite trivial to
compute, or one can just look up appropriate values for their use case.
## Implementation
I'll be using Python, which has the nifty ability of representing bitsets
through its built-in big integers quite easily.
We'll be assuming a `BIT_COUNT` of 64 here, but the implementation can easily be
tweaked to use a different number, or even change it at construction time.
### Representation
A `BloomFilter` is just a set of bits and a list of hash functions.
```python
BIT_COUNT = 64
class BloomFilter[T]:
_bits: int
_hash_functions: list[Callable[[T], int]]
def __init__(self, hash_functions: list[Callable[[T], int]]) -> None:
# Filter is initially empty
self._bits = 0
self._hash_functions = hash_functions
```