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author | Yanbo Liang <ybliang8@gmail.com> | 2016-10-26 09:28:28 -0700 |
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committer | Yanbo Liang <ybliang8@gmail.com> | 2016-10-26 09:28:28 -0700 |
commit | 312ea3f7f65532818e11016d6d780ad47485175f (patch) | |
tree | 49e8c9c04211024887bede0244bb8f87b88239a9 /mllib/src | |
parent | 4bee9540790a40acb74db4b0b44c364c4b3f537d (diff) | |
download | spark-312ea3f7f65532818e11016d6d780ad47485175f.tar.gz spark-312ea3f7f65532818e11016d6d780ad47485175f.tar.bz2 spark-312ea3f7f65532818e11016d6d780ad47485175f.zip |
[SPARK-17748][FOLLOW-UP][ML] Reorg variables of WeightedLeastSquares.
## What changes were proposed in this pull request?
This is follow-up work of #15394.
Reorg some variables of ```WeightedLeastSquares``` and fix one minor issue of ```WeightedLeastSquaresSuite```.
## How was this patch tested?
Existing tests.
Author: Yanbo Liang <ybliang8@gmail.com>
Closes #15621 from yanboliang/spark-17748.
Diffstat (limited to 'mllib/src')
-rw-r--r-- | mllib/src/main/scala/org/apache/spark/ml/optim/WeightedLeastSquares.scala | 139 | ||||
-rw-r--r-- | mllib/src/test/scala/org/apache/spark/ml/optim/WeightedLeastSquaresSuite.scala | 15 |
2 files changed, 86 insertions, 68 deletions
diff --git a/mllib/src/main/scala/org/apache/spark/ml/optim/WeightedLeastSquares.scala b/mllib/src/main/scala/org/apache/spark/ml/optim/WeightedLeastSquares.scala index 2223f126f1..90c24e1b59 100644 --- a/mllib/src/main/scala/org/apache/spark/ml/optim/WeightedLeastSquares.scala +++ b/mllib/src/main/scala/org/apache/spark/ml/optim/WeightedLeastSquares.scala @@ -101,23 +101,19 @@ private[ml] class WeightedLeastSquares( summary.validate() logInfo(s"Number of instances: ${summary.count}.") val k = if (fitIntercept) summary.k + 1 else summary.k + val numFeatures = summary.k val triK = summary.triK val wSum = summary.wSum - val bBar = summary.bBar - val bbBar = summary.bbBar - val aBar = summary.aBar - val aStd = summary.aStd - val abBar = summary.abBar - val aaBar = summary.aaBar - val numFeatures = abBar.size + val rawBStd = summary.bStd + val rawBBar = summary.bBar // if b is constant (rawBStd is zero), then b cannot be scaled. In this case - // setting bStd=abs(bBar) ensures that b is not scaled anymore in l-bfgs algorithm. - val bStd = if (rawBStd == 0.0) math.abs(bBar) else rawBStd + // setting bStd=abs(rawBBar) ensures that b is not scaled anymore in l-bfgs algorithm. + val bStd = if (rawBStd == 0.0) math.abs(rawBBar) else rawBStd if (rawBStd == 0) { - if (fitIntercept || bBar == 0.0) { - if (bBar == 0.0) { + if (fitIntercept || rawBBar == 0.0) { + if (rawBBar == 0.0) { logWarning(s"Mean and standard deviation of the label are zero, so the coefficients " + s"and the intercept will all be zero; as a result, training is not needed.") } else { @@ -126,7 +122,7 @@ private[ml] class WeightedLeastSquares( s"training is not needed.") } val coefficients = new DenseVector(Array.ofDim(numFeatures)) - val intercept = bBar + val intercept = rawBBar val diagInvAtWA = new DenseVector(Array(0D)) return new WeightedLeastSquaresModel(coefficients, intercept, diagInvAtWA, Array(0D)) } else { @@ -137,53 +133,70 @@ private[ml] class WeightedLeastSquares( } } - // scale aBar to standardized space in-place - val aBarValues = aBar.values - var j = 0 - while (j < numFeatures) { - if (aStd(j) == 0.0) { - aBarValues(j) = 0.0 - } else { - aBarValues(j) /= aStd(j) - } - j += 1 - } + val bBar = summary.bBar / bStd + val bbBar = summary.bbBar / (bStd * bStd) - // scale abBar to standardized space in-place - val abBarValues = abBar.values + val aStd = summary.aStd val aStdValues = aStd.values - j = 0 - while (j < numFeatures) { - if (aStdValues(j) == 0.0) { - abBarValues(j) = 0.0 - } else { - abBarValues(j) /= (aStdValues(j) * bStd) + + val aBar = { + val _aBar = summary.aBar + val _aBarValues = _aBar.values + var i = 0 + // scale aBar to standardized space in-place + while (i < numFeatures) { + if (aStdValues(i) == 0.0) { + _aBarValues(i) = 0.0 + } else { + _aBarValues(i) /= aStdValues(i) + } + i += 1 } - j += 1 + _aBar } + val aBarValues = aBar.values - // scale aaBar to standardized space in-place - val aaBarValues = aaBar.values - j = 0 - var p = 0 - while (j < numFeatures) { - val aStdJ = aStdValues(j) + val abBar = { + val _abBar = summary.abBar + val _abBarValues = _abBar.values var i = 0 - while (i <= j) { - val aStdI = aStdValues(i) - if (aStdJ == 0.0 || aStdI == 0.0) { - aaBarValues(p) = 0.0 + // scale abBar to standardized space in-place + while (i < numFeatures) { + if (aStdValues(i) == 0.0) { + _abBarValues(i) = 0.0 } else { - aaBarValues(p) /= (aStdI * aStdJ) + _abBarValues(i) /= (aStdValues(i) * bStd) } - p += 1 i += 1 } - j += 1 + _abBar } + val abBarValues = abBar.values - val bBarStd = bBar / bStd - val bbBarStd = bbBar / (bStd * bStd) + val aaBar = { + val _aaBar = summary.aaBar + val _aaBarValues = _aaBar.values + var j = 0 + var p = 0 + // scale aaBar to standardized space in-place + while (j < numFeatures) { + val aStdJ = aStdValues(j) + var i = 0 + while (i <= j) { + val aStdI = aStdValues(i) + if (aStdJ == 0.0 || aStdI == 0.0) { + _aaBarValues(p) = 0.0 + } else { + _aaBarValues(p) /= (aStdI * aStdJ) + } + p += 1 + i += 1 + } + j += 1 + } + _aaBar + } + val aaBarValues = aaBar.values val effectiveRegParam = regParam / bStd val effectiveL1RegParam = elasticNetParam * effectiveRegParam @@ -191,11 +204,11 @@ private[ml] class WeightedLeastSquares( // add L2 regularization to diagonals var i = 0 - j = 2 + var j = 2 while (i < triK) { var lambda = effectiveL2RegParam if (!standardizeFeatures) { - val std = aStd(j - 2) + val std = aStdValues(j - 2) if (std != 0.0) { lambda /= (std * std) } else { @@ -209,8 +222,9 @@ private[ml] class WeightedLeastSquares( i += j j += 1 } - val aa = getAtA(aaBar.values, aBar.values) - val ab = getAtB(abBar.values, bBarStd) + + val aa = getAtA(aaBarValues, aBarValues) + val ab = getAtB(abBarValues, bBar) val solver = if ((solverType == WeightedLeastSquares.Auto && elasticNetParam != 0.0 && regParam != 0.0) || (solverType == WeightedLeastSquares.QuasiNewton)) { @@ -237,22 +251,23 @@ private[ml] class WeightedLeastSquares( val solution = solver match { case cholesky: CholeskySolver => try { - cholesky.solve(bBarStd, bbBarStd, ab, aa, aBar) + cholesky.solve(bBar, bbBar, ab, aa, aBar) } catch { // if Auto solver is used and Cholesky fails due to singular AtA, then fall back to - // quasi-newton solver + // Quasi-Newton solver. case _: SingularMatrixException if solverType == WeightedLeastSquares.Auto => logWarning("Cholesky solver failed due to singular covariance matrix. " + "Retrying with Quasi-Newton solver.") // ab and aa were modified in place, so reconstruct them - val _aa = getAtA(aaBar.values, aBar.values) - val _ab = getAtB(abBar.values, bBarStd) + val _aa = getAtA(aaBarValues, aBarValues) + val _ab = getAtB(abBarValues, bBar) val newSolver = new QuasiNewtonSolver(fitIntercept, maxIter, tol, None) - newSolver.solve(bBarStd, bbBarStd, _ab, _aa, aBar) + newSolver.solve(bBar, bbBar, _ab, _aa, aBar) } case qn: QuasiNewtonSolver => - qn.solve(bBarStd, bbBarStd, ab, aa, aBar) + qn.solve(bBar, bbBar, ab, aa, aBar) } + val (coefficientArray, intercept) = if (fitIntercept) { (solution.coefficients.slice(0, solution.coefficients.length - 1), solution.coefficients.last * bStd) @@ -271,7 +286,11 @@ private[ml] class WeightedLeastSquares( // aaInv is a packed upper triangular matrix, here we get all elements on diagonal val diagInvAtWA = solution.aaInv.map { inv => new DenseVector((1 to k).map { i => - val multiplier = if (i == k && fitIntercept) 1.0 else aStdValues(i - 1) * aStdValues(i - 1) + val multiplier = if (i == k && fitIntercept) { + 1.0 + } else { + aStdValues(i - 1) * aStdValues(i - 1) + } inv(i + (i - 1) * i / 2 - 1) / (wSum * multiplier) }.toArray) }.getOrElse(new DenseVector(Array(0D))) @@ -280,7 +299,7 @@ private[ml] class WeightedLeastSquares( solution.objectiveHistory.getOrElse(Array(0D))) } - /** Construct A^T^ A from summary statistics. */ + /** Construct A^T^ A (append bias if necessary). */ private def getAtA(aaBar: Array[Double], aBar: Array[Double]): DenseVector = { if (fitIntercept) { new DenseVector(Array.concat(aaBar, aBar, Array(1.0))) @@ -289,7 +308,7 @@ private[ml] class WeightedLeastSquares( } } - /** Construct A^T^ b from summary statistics. */ + /** Construct A^T^ b (append bias if necessary). */ private def getAtB(abBar: Array[Double], bBar: Double): DenseVector = { if (fitIntercept) { new DenseVector(Array.concat(abBar, Array(bBar))) diff --git a/mllib/src/test/scala/org/apache/spark/ml/optim/WeightedLeastSquaresSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/optim/WeightedLeastSquaresSuite.scala index 3cdab03279..093d02ea7a 100644 --- a/mllib/src/test/scala/org/apache/spark/ml/optim/WeightedLeastSquaresSuite.scala +++ b/mllib/src/test/scala/org/apache/spark/ml/optim/WeightedLeastSquaresSuite.scala @@ -361,14 +361,13 @@ class WeightedLeastSquaresSuite extends SparkFunSuite with MLlibTestSparkContext for (fitIntercept <- Seq(false, true); standardization <- Seq(false, true); (lambda, alpha) <- Seq((0.0, 0.0), (0.5, 0.0), (0.5, 0.5), (0.5, 1.0))) { - for (solver <- Seq(WeightedLeastSquares.Auto, WeightedLeastSquares.Cholesky)) { - val wls = new WeightedLeastSquares(fitIntercept, regParam = lambda, elasticNetParam = alpha, - standardizeFeatures = standardization, standardizeLabel = true, - solverType = WeightedLeastSquares.QuasiNewton) - val model = wls.fit(constantFeaturesInstances) - val actual = Vectors.dense(model.intercept, model.coefficients(0), model.coefficients(1)) - assert(actual ~== expectedQuasiNewton(idx) absTol 1e-6) - } + val wls = new WeightedLeastSquares(fitIntercept, regParam = lambda, elasticNetParam = alpha, + standardizeFeatures = standardization, standardizeLabel = true, + solverType = WeightedLeastSquares.QuasiNewton) + val model = wls.fit(constantFeaturesInstances) + val actual = Vectors.dense(model.intercept, model.coefficients(0), model.coefficients(1)) + assert(actual ~== expectedQuasiNewton(idx) absTol 1e-6) + idx += 1 } } |