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author | Sean Owen <sowen@cloudera.com> | 2014-01-18 12:53:01 +0000 |
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committer | Sean Owen <sowen@cloudera.com> | 2014-01-18 12:53:01 +0000 |
commit | e91ad3f164b64e727f41ced6ae20d70ca4c92521 (patch) | |
tree | 717f4906a9cca74d87e14587eeb218895d49b986 /mllib/src | |
parent | d749d472b37448edb322bc7208a3db925c9a4fc2 (diff) | |
download | spark-e91ad3f164b64e727f41ced6ae20d70ca4c92521.tar.gz spark-e91ad3f164b64e727f41ced6ae20d70ca4c92521.tar.bz2 spark-e91ad3f164b64e727f41ced6ae20d70ca4c92521.zip |
Correct L2 regularized weight update with canonical form
Diffstat (limited to 'mllib/src')
-rw-r--r-- | mllib/src/main/scala/org/apache/spark/mllib/optimization/Updater.scala | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/optimization/Updater.scala b/mllib/src/main/scala/org/apache/spark/mllib/optimization/Updater.scala index 4c51f4f881..37124f261e 100644 --- a/mllib/src/main/scala/org/apache/spark/mllib/optimization/Updater.scala +++ b/mllib/src/main/scala/org/apache/spark/mllib/optimization/Updater.scala @@ -86,13 +86,17 @@ class L1Updater extends Updater { /** * Updater that adjusts the learning rate and performs L2 regularization + * + * See, for example, explanation of gradient and loss with L2 regularization on slide 21-22 + * of <a href="http://people.cs.umass.edu/~sheldon/teaching/2012fa/ml/files/lec7-annotated.pdf"> + * these slides</a>. */ class SquaredL2Updater extends Updater { override def compute(weightsOld: DoubleMatrix, gradient: DoubleMatrix, stepSize: Double, iter: Int, regParam: Double): (DoubleMatrix, Double) = { val thisIterStepSize = stepSize / math.sqrt(iter) val normGradient = gradient.mul(thisIterStepSize) - val newWeights = weightsOld.sub(normGradient).div(2.0 * thisIterStepSize * regParam + 1.0) + val newWeights = weightsOld.mul(1.0 - 2.0 * thisIterStepSize * regParam).sub(normGradient) (newWeights, pow(newWeights.norm2, 2.0) * regParam) } } |