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more descriptibe arguments II

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This commit is contained in:
Isidro Arias 2023-04-06 17:26:25 +02:00
parent 5d460aa79e
commit cc54095c47
1 changed files with 12 additions and 11 deletions
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23
data_structures/hashing/bloom_filter.py
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@ -70,27 +70,28 @@ def random_string(size: int) -> str:
return "".join(choices(ascii_lowercase + " ", k=size))
def test_probability(bits: int = 64, n: int = 20) -> None:
b = Bloom(size=bits)
def test_probability(filter_bits: int = 64, added_elements: int = 20) -> None:
b = Bloom(size=filter_bits)
k = len(b.HASH_FUNCTIONS)
estimated_error_rate_beforehand = (1 - (1 - 1 / bits) ** (k * n)) ** k
added = {random_string(10) for i in range(n)}
for a in added:
b.add(a)
n_ones = bin(b.bitstring).count("1")
estimated_error_rate = (n_ones / bits) ** k
estimated_error_rate_beforehand = (
1 - (1 - 1 / filter_bits) ** (k * added_elements)
) ** k
not_added = {random_string(10) for i in range(1000)}
for _ in range(added_elements):
b.add(not_added.pop())
n_ones = bin(b.bitstring).count("1")
estimated_error_rate = (n_ones / filter_bits) ** k
errors = 0
for string in not_added:
if b.exists(string):
errors += 1
error_rate = errors / len(not_added)
print(f"total = {len(not_added)}, errors = {errors}, error_rate = {error_rate}")
print(f"error_rate = {errors}/{len(not_added)} = {error_rate}")
print(f"{estimated_error_rate=}")
print(f"{estimated_error_rate_beforehand=}")