daft.functions.simhash#

def simhash(
    text: Expression,
    *,
    ngram_size: int = 3,
    hash_function: Literal["murmurhash3", "xxhash", "xxhash32", "xxhash64", "xxhash3_64", "sha1"] = "xxhash3_64",
) -> Expression:
    """Compute a SimHash fingerprint of the input text.

    SimHash produces a 64-bit locality-sensitive hash from character n-grams.
    Similar texts produce fingerprints with small bitwise Hamming distance,
    making it useful for near-duplicate detection.

    Args:
        text (String Expression): The expression to hash.
        ngram_size (int, default=3): Character n-gram size. Defaults to 3.
        hash_function (str, default="xxhash3_64"): Hash function for n-grams. One of "murmurhash3", "xxhash" (alias for "xxhash3_64"), "xxhash32", "xxhash64", "xxhash3_64", or "sha1". Defaults to "xxhash3_64".

    Returns:
        Expression (UInt64 Expression): SimHash fingerprint.
    """
    return Expression._call_builtin_scalar_fn("simhash", text, ngram_size=ngram_size, hash_function=hash_function)