GitHub user cestella opened a pull request:
https://github.com/apache/metron/pull/867
METRON-1350: Add reservoir sampling functions to Stellar
## Contributor Comments
Sampling capabilities would fit very well with the profiler and enable
algorithms that do not necessarily support our existing probabilistic sketches.
We should add a reservoir sampler and utilities to merge and resample.
You can play with `SAMPLE_INIT`, `SAMPLE_ADD`, `SAMPLE_MERGE` and
`SAMPLE_GET` via the REPL:
```
[Stellar]>>> ?SAMPLE_ADD
SAMPLE_ADD
Description: Add to a sample
Arguments:
sampler - Sampler to use. If null, then a default Uniform sampler is
created
o - The value to add. If o is an Iterable, then each item is added.
Returns:
[Stellar]>>> s_10 := SAMPLE_INIT(10)
[Stellar]>>> sample := REDUCE( [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 ], (s,
x) -> SAMPLE_ADD(s, x), SAMPLE_INIT(5))
[Stellar]>>> SAMPLE_GET(sample)
[6, 8, 11, 4, 5]
[Stellar]>>> SAMPLE_ADD(s_10, [5, 2, 5, 7, 10 ])
org.apache.metron.statistics.sampling.UniformSampler@3d8d06c0
[Stellar]>>> SAMPLE_GET(SAMPLE_ADD(s_10, [5, 2, 5, 7, 10 ]))
[5, 2, 5, 7, 10, 5, 2, 5, 7, 10]
```
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This closes #867
----
commit 7e1a19e29f86a23140aa46291f0083409ddac40d
Author: cstella <[email protected]>
Date: 2017-12-13T20:59:40Z
METRON-1350: Add reservoir sampling functions to Stellar
----
---
