Github user mengxr commented on a diff in the pull request:
https://github.com/apache/spark/pull/2294#discussion_r17709081
--- 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
--- End diff --
Let's write down the contract. `rowIndices` should be strictly increasing
for each column.
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