Github user mengxr commented on a diff in the pull request: https://github.com/apache/spark/pull/2294#discussion_r17709085 --- Diff: mllib/src/main/scala/org/apache/spark/mllib/linalg/Matrices.scala --- @@ -59,11 +93,113 @@ trait Matrix extends Serializable { */ class DenseMatrix(val numRows: Int, val numCols: Int, val values: Array[Double]) extends Matrix { - require(values.length == numRows * numCols) + require(values.length == numRows * numCols, "The number of values supplied doesn't match the " + + s"size of the matrix! values.length: ${values.length}, numRows * numCols: ${numRows * numCols}") override def toArray: Array[Double] = values - private[mllib] override def toBreeze: BM[Double] = new BDM[Double](numRows, numCols, values) + private[mllib] def toBreeze: BM[Double] = new BDM[Double](numRows, numCols, values) + + private[mllib] def apply(i: Int): Double = values(i) + + private[mllib] def apply(i: Int, j: Int): Double = values(index(i, j)) + + private[mllib] def index(i: Int, j: Int): Int = i + numRows * j + + private[mllib] def update(i: Int, j: Int, v: Double){ + values(index(i, j)) = v + } + + override def copy = new DenseMatrix(numRows, numCols, values.clone()) +} + +/** + * Column-majored sparse matrix. + * The entry values are stored in Compressed Sparse Column (CSC) format. + * For example, the following matrix + * {{{ + * 1.0 0.0 4.0 + * 0.0 3.0 5.0 + * 2.0 0.0 6.0 + * }}} + * is stored as `values: [1.0, 2.0, 3.0, 4.0, 5.0, 6.0]`, + * `rowIndices=[0, 2, 1, 0, 1, 2]`, `colPointers=[0, 2, 3, 6]`. + * + * @param numRows number of rows + * @param numCols number of columns + * @param colPtrs the index corresponding to the start of a new column + * @param rowIndices the row index of the entry + * @param values non-zero matrix entries in column major + */ +class SparseMatrix( + val numRows: Int, + val numCols: Int, + val colPtrs: Array[Int], + val rowIndices: Array[Int], + val values: Array[Double]) extends Matrix { + + require(values.length == rowIndices.length, "The number of row indices and values don't match! " + + s"values.length: ${values.length}, rowIndices.length: ${rowIndices.length}") + require(colPtrs.length == numCols + 1, "The length of the column indices should be the " + + s"number of columns + 1. Currently, colPointers.length: ${colPtrs.length}, " + + s"numCols: $numCols") + + override def toArray: Array[Double] = { + val arr = Array.fill(numRows * numCols)(0.0) + var j = 0 + while (j < numCols) { + var i = colPtrs(j) + val indEnd = colPtrs(j + 1) + val offset = j * numRows + while (i < indEnd) { + val rowIndex = rowIndices(i) + arr(offset + rowIndex) = values(i) + i += 1 + } + j += 1 + } + arr + } + + private[mllib] def toBreeze: BM[Double] = + new BSM[Double](values, numRows, numCols, colPtrs, rowIndices) + + private[mllib] def apply(i: Int): Double = values(i) --- End diff -- ditto: remove this method and use `.values(i)` directly
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