mmhash3 (MurmurHash3)

3.0.1 · maintenance · verified Mon Apr 13

mmhash3 is a Python wrapper for MurmurHash (MurmurHash3), a collection of fast and robust non-cryptographic hash functions. This specific library (version 3.0.1, last updated Oct 2022) is a fork of the original 'mmh3' library, which was considered unmaintained at the time of its creation. For a more actively developed and current version of a MurmurHash3 Python wrapper, users often look to the 'mmh3' package (pypi.org/project/mmh3).

Warnings

gotcha The library is installed via `pip install mmhash3`, but the Python module to import is `mmh3`. Importing `mmhash3` will fail.
Fix: Always use `import mmh3` in your Python code.
breaking Results of 32-bit `mmh3.hash()` changed in version 2.1 (prior to 3.0.1). If your application relies on specific hash values from very old `mmh3` versions (pre-2.1), the results from `mmhash3` (v3.0.1) will differ.
Fix: Ensure your tests or dependent systems are updated to expect the hash values generated by current versions of MurmurHash3, or explicitly use older library versions if exact historical compatibility is critical and understood.
gotcha By default, `mmh3.hash()` and `mmh3.hash64()` return signed integers, while `mmh3.hash128()` returns an unsigned integer. This can lead to different results compared to other MurmurHash3 implementations that might default to unsigned values. The `mmh3.hash64()` function also returns two 64-bit values as a tuple.
Fix: Use the `signed=False` keyword argument for `mmh3.hash()` or `mmh3.hash64()` to obtain unsigned values if needed for compatibility with other systems or libraries. Be aware that `hash64` always returns two values.
gotcha The behavior of seed values changed around version 2.4 (prior to 3.0.1), shifting from signed to unsigned 32-bit integers. While existing 32-bit signed seeds *should* yield the same results, using non-32-bit or intentionally negative seeds without careful consideration may lead to unexpected results or compatibility issues.
Fix: Ensure seed values are 32-bit integers. For compatibility with older systems using negative 32-bit seeds, ensure the implicit conversion behavior is understood.
deprecated This `mmhash3` package (version 3.0.1) is a fork of an older, unmaintained `mmh3` library. For active development, newer Python versions support, and potential performance improvements, consider using the actively maintained `mmh3` package (github.com/hajimes/mmh3, pypi.org/project/mmh3) which is currently at version 5.x.x.
Fix: Evaluate migrating to the actively maintained `mmh3` library (pip install mmh3) for ongoing support and features. Be aware of potential breaking changes if migrating, especially regarding endianness (mmh3 v4.0.0 made it endian-neutral) and seed handling.

Install

pip install mmhash3 Install mmhash3

Imports

hash
```
import mmh3
mmh3.hash('your_string')
```
Despite the package name 'mmhash3', the main module to import is 'mmh3', consistent with its origins as a fork of the 'mmh3' library. Attempting to import 'mmhash3' directly will result in an ImportError.

Quickstart

Demonstrates basic hashing of strings using the default 32-bit algorithm, with and without a seed, and obtaining a 128-bit hash.

import mmh3

# Hash a string to a 32-bit signed integer
hash_value_32_bit = mmh3.hash("hello world")
print(f"32-bit hash: {hash_value_32_bit}")

# Hash with a seed
hash_value_seeded = mmh3.hash("hello world", 42)
print(f"32-bit hash with seed 42: {hash_value_seeded}")

# Get a 32-bit unsigned integer hash
hash_value_unsigned = mmh3.hash("hello world", signed=False)
print(f"32-bit unsigned hash: {hash_value_unsigned}")

# Get a 128-bit hash as a single unsigned integer
hash_value_128_bit = mmh3.hash128("hello world", 0)
print(f"128-bit hash: {hash_value_128_bit}")

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