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From cestella <>
Subject [GitHub] metron pull request #872: METRON-1366: Add an entropy stellar function
Date Fri, 15 Dec 2017 23:34:12 GMT
GitHub user cestella opened a pull request:

    METRON-1366: Add an entropy stellar function

    ## Contributor Comments
    Trending entropy for various volumetric statistics (e.g. netflow data) has been a useful
metric for intrusion detection (see
To wit, it makes some sense to add an entropy calculation for Stellar. Used in conjunction
with the profiler and an outlier detector, we can recreate the work of Lakhina referenced
    You can validate this from the REPL:
    * `IT_ENTROPY({ 'a' : 10, 'b' : 5, 'c' : 5} )` should yield `1.5`
      * By the definition of Entropy: `H(X) = -p(a)*log_2(p(a)) - p(b)*log_2(p(b)) - p(c)*log_2(p(c))
= -0.5*-1 - 0.25*-2 - 0.25*-2 = 1.5`
    * `IT_ENTROPY({})` should yield `0.0`
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You can merge this pull request into a Git repository by running:

    $ git pull entropy

Alternatively you can review and apply these changes as the patch at:

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #872
commit d4494854e482e2532f707b28ef2f891d13e129f3
Author: cstella <>
Date:   2017-12-15T23:25:50Z

    Added entropy function.



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