NOTE: This is a fairly literal translation/port of java-hll
to Python. Internally, bytes are represented as Java-style bytes (-128 to 127) rather than Python-style bytes (0 to 255).
Also this implementation is quite slow: for example, in Java
HLLSerializationTest takes 12 seconds to run
while in Python
test_hll_serialization takes 1.5 hours to run (about 400x slower).
- Runs on: Python 2.7 and 3
- Free software: MIT license
- Documentation: https://python-hll.readthedocs.io
- GitHub: https://github.com/AdRoll/python-hll
See java-hll for an overview of what HLLs are and how they work.
Hashing and adding a value to a new HLL:
from python_hll.hll import HLL import mmh3 value_to_hash = 'foo' hashed_value = mmh3.hash(value_to_hash) hll = HLL(13, 5) # log2m=13, regwidth=5 hll.add_raw(hashed_value)
Retrieving the cardinality of an HLL:
cardinality = hll.cardinality()
Unioning two HLLs together (and retrieving the resulting cardinality):
hll1 = HLL(13, 5) # log2m=13, regwidth=5 hll2 = HLL(13, 5) # log2m=13, regwidth=5 # ... (add values to both sets) ... hll1.union(hll2) # modifies hll1 to contain the union cardinalityUnion = hll1.cardinality()
from python_hll.util import NumberUtil input = '\\x128D7FFFFFFFFFF6A5C420' hex_string = input[2:] hll = HLL.from_bytes(NumberUtil.from_hex(hex_string, 0, len(hex_string)))
bytes = hll.to_bytes() output = "\\x" + NumberUtil.to_hex(bytes, 0, len(bytes))
Also see the API documentation.
See Contributing for how to get started building, testing, and deploying the code.