Question

如何创建SparseVector和密集的矢量表示

如果DenseVector是：

denseV = np.array([0., 3., 0., 4.])

稀疏矢量表示是什么？

Answer 1

除非我彻底误解了你的疑问，否则MLlib data type documentation非常清楚地说明了这一点：

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import org.apache.spark.mllib.linalg.Vector; import org.apache.spark.mllib.linalg.Vectors; // Create a dense vector (1.0, 0.0, 3.0). Vector dv = Vectors.dense(1.0, 0.0, 3.0); // Create a sparse vector (1.0, 0.0, 3.0) by specifying its indices and values corresponding to nonzero entries. Vector sv = Vectors.sparse(3, new int[] {0, 2}, new double[] {1.0, 3.0});的第二个参数是索引数组，第三个参数是这些索引中实际值的数组。

Answer 2

稀疏向量是指向量中有很多值为零。虽然密集向量是指向量中的大多数值都不为零。

如果必须从指定的密集向量创建稀疏向量，请使用以下语法：

Vector sparseVector = Vectors.sparse(4, new int[] {1, 3}, new double[] {3.0, 4.0});

稀疏的矢量与密集的矢量

2 个答案: