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A Python implementation of the Recordinality sketch

Project description

A Python implementation of the Recordinality sketch for cardinality estimation and stream sampling. Inspired by C. Scott Andreas’s implementation, but powered by SipHash-2-4 rather than MurmurHash3. In particular, this project uses two other libraries of mine: csiphash and cskipdict.

Installation

pip install recordinality

Usage

You can use the command-line application, which will read lines of text incrementally from stdin, printing the stream’s cardinality (or a random sample) once the pipe is closed:

$ recordinality -k <sketch-size> [-h|--hash-key <hash-key>] [-s|--sample] < input-lines.txt
3574
$ cat input-lines.txt | sort -u | wc -l
3556

SipHash allows the specification of a ‘secret key’ (used here as more of a hash seed); if provided it should be either a 16-char ASCII string or 32-char hexadecimal string.

You can also import the Recordinality class in Python:

>>> from recordinality import Recordinality
>>> sketch = Recordinality(size=512)
>>> for observation in input_observations:
...     sketch.add(observation)
>>> print(sketch.cardinality())
3574
>>> print(sketch.k_sample)
['strife', 'bragging', 'knight?', ...]

Unlicense

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to http://unlicense.org/

Project details


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