Spark Rowmatrix 分布式矩阵

import org.apache.spark.rdd.RDD
import org.apache.spark.mllib.linalg.Vectors
import org.apache.spark.mllib.linalg.distributed.RowMatrix
 
val df1 = Seq(
     |       (1.0, 2.0, 3.0),
     |       (1.1, 2.1, 3.1),
     |       (1.2, 2.2, 3.2)).toDF("c1", "c2", "c3")
df1: org.apache.spark.sql.DataFrame = [c1: double, c2: double ... 1 more field]
 
df1.show
+---+---+---+
| c1| c2| c3|
+---+---+---+
|1.0|2.0|3.0|
|1.1|2.1|3.1|
|1.2|2.2|3.2|
+---+---+---+
                        
// DataFrame转换成RDD[Vector]
val rowsVector= df1.rdd.map {
            x =>
              Vectors.dense(
                x(0).toString().toDouble,
                x(1).toString().toDouble,
                x(2).toString().toDouble)
          }
rowsVector: org.apache.spark.rdd.RDD[org.apache.spark.mllib.linalg.Vector] = MapPartitionsRDD[4] at map
 
// Create a RowMatrix from an RDD[Vector].
val mat1: RowMatrix = new RowMatrix(rowsVector)
mat1: org.apache.spark.mllib.linalg.distributed.RowMatrix = org.apache.spark.mllib.linalg.distributed.RowMatrix@7ba821ef
 
// Get its size.
val m = mat1.numRows()
m: Long = 3                                                                    
 
val n = mat1.numCols()
n: Long = 3
 
// 将RowMatrix转换成DataFrame
val resDF = mat1.rows.map {
            x =>
             (x(0).toDouble,
                x(1).toDouble,
                x(2).toDouble)
          }.toDF("c1", "c2", "c3")
resDF: org.apache.spark.sql.DataFrame = [c1: double, c2: double ... 1 more field]
 
resDF.show
+---+---+---+
| c1| c2| c3|
+---+---+---+
|1.0|2.0|3.0|
|1.1|2.1|3.1|
|1.2|2.2|3.2|
+---+---+---+
 
 
mat1.rows.collect().take(10)
res3: Array[org.apache.spark.mllib.linalg.Vector] = Array([1.0,2.0,3.0], [1.1,2.1,3.1], [1.2,2.2,3.2])

　　

CoordinateMatrix坐标矩阵

import org.apache.spark.rdd.RDD
import org.apache.spark.mllib.linalg.distributed.{CoordinateMatrix, MatrixEntry}
 
// 第一列：行坐标；第二列：列坐标；第三列：矩阵元素
val df = Seq(
     |       (0, 0, 1.1), (0, 1, 1.2), (0, 2, 1.3),
     |       (1, 0, 2.1), (1, 1, 2.2), (1, 2, 2.3),
     |       (2, 0, 3.1), (2, 1, 3.2), (2, 2, 3.3),
     |       (3, 0, 4.1), (3, 1, 4.2), (3, 2, 4.3)).toDF("row", "col", "value")
df: org.apache.spark.sql.DataFrame = [row: int, col: int ... 1 more field]
 
df.show
+---+---+-----+
|row|col|value|
+---+---+-----+
|  0|  0|  1.1|
|  0|  1|  1.2|
|  0|  2|  1.3|
|  1|  0|  2.1|
|  1|  1|  2.2|
|  1|  2|  2.3|
|  2|  0|  3.1|
|  2|  1|  3.2|
|  2|  2|  3.3|
|  3|  0|  4.1|
|  3|  1|  4.2|
|  3|  2|  4.3|
+---+---+-----+
 
// 生成入口矩阵
val entr = df.rdd.map { x =>
     |       val a = x(0).toString().toLong
     |       val b = x(1).toString().toLong
     |       val c = x(2).toString().toDouble
     |       MatrixEntry(a, b, c)
     |     }
entr: org.apache.spark.rdd.RDD[org.apache.spark.mllib.linalg.distributed.MatrixEntry] = MapPartitionsRDD[20] at map
 
// 生成坐标矩阵
val mat: CoordinateMatrix = new CoordinateMatrix(entr)
mat: org.apache.spark.mllib.linalg.distributed.CoordinateMatrix = org.apache.spark.mllib.linalg.distributed.CoordinateMatrix@5381deec
 
mat.numRows()
res5: Long = 4                                                                 
 
mat.numCols()
res6: Long = 3
 
mat.entries.collect().take(10)
res7: Array[org.apache.spark.mllib.linalg.distributed.MatrixEntry] = Array(MatrixEntry(0,0,1.1), MatrixEntry(0,1,1.2), MatrixEntry(0,2,1.3), MatrixEntry(1,0,2.1), MatrixEntry(1,1,2.2), MatrixEntry(1,2,2.3), MatrixEntry(2,0,3.1), MatrixEntry(2,1,3.2), MatrixEntry(2,2,3.3), MatrixEntry(3,0,4.1))
 
// 坐标矩阵转成，带行索引的DataFrame，行索引为行坐标
val t = mat.toIndexedRowMatrix().rows.map { x =>
     |       val v=x.vector
     |       (x.index,v(0).toDouble, v(1).toDouble, v(2).toDouble)
     |     }
t: org.apache.spark.rdd.RDD[(Long, Double, Double, Double)] = MapPartitionsRDD[33] at map
 
t.toDF().show
+---+---+---+---+                                                              
| _1| _2| _3| _4|
+---+---+---+---+
|  0|1.1|1.2|1.3|
|  1|2.1|2.2|2.3|
|  2|3.1|3.2|3.3|
|  3|4.1|4.2|4.3|
+---+---+---+---+
 
// 坐标矩阵转成DataFrame
val t1 = mat.toRowMatrix().rows.map { x =>
     |       (x(0).toDouble, x(1).toDouble, x(2).toDouble)
     |     }
t1: org.apache.spark.rdd.RDD[(Double, Double, Double)] = MapPartitionsRDD[26] at map
 
t1.toDF().show
+---+---+---+
| _1| _2| _3|
+---+---+---+
|1.1|1.2|1.3|
|3.1|3.2|3.3|
|2.1|2.2|2.3|
|4.1|4.2|4.3|
+---+---+---+