org.apache.sysds.runtime.io

## Class MatrixWriter

- java.lang.Object
- - org.apache.sysds.runtime.io.MatrixWriter

- Direct Known Subclasses:
    WriterBinaryBlock, WriterMatrixMarket, WriterTextCell, WriterTextCSV, WriterTextLIBSVM

      public abstract class MatrixWriter
      extends Object

  Base class for all format-specific matrix writers. Every writer is required to implement the basic write functionality but might provide additional custom functionality. Any non-default parameters (e.g., CSV read properties) should be passed into custom constructors. There is also a factory for creating format-specific writers.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `MatrixWriter()`

  - ### Method Summary

    All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static MatrixBlock[]` | `createMatrixBlocksForReuse(long rlen, long clen, int blen, boolean sparse, long nonZeros)`
    `static MatrixBlock` | `getMatrixBlockForReuse(MatrixBlock[] blocks, int rows, int cols, int blen)`
    `abstract void` | `writeEmptyMatrixToHDFS(String fname, long rlen, long clen, int blen)` Writes a minimal entry to represent an empty matrix on hdfs.
    `void` | `writeMatrixToHDFS(MatrixBlock src, String fname, long rlen, long clen, int blen, long nnz)`
    `abstract void` | `writeMatrixToHDFS(MatrixBlock src, String fname, long rlen, long clen, int blen, long nnz, boolean diag)`

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### MatrixWriter

          public MatrixWriter()

  - ### Method Detail

    - #### writeMatrixToHDFS

          public void writeMatrixToHDFS(MatrixBlock src,
                                        String fname,
                                        long rlen,
                                        long clen,
                                        int blen,
                                        long nnz)
                                 throws IOException

      Throws:
        `IOException`

    - #### writeMatrixToHDFS

          public abstract void writeMatrixToHDFS(MatrixBlock src,
                                                 String fname,
                                                 long rlen,
                                                 long clen,
                                                 int blen,
                                                 long nnz,
                                                 boolean diag)
                                          throws IOException

      Throws:
        `IOException`

    - #### writeEmptyMatrixToHDFS

          public abstract void writeEmptyMatrixToHDFS(String fname,
                                                      long rlen,
                                                      long clen,
                                                      int blen)
                                               throws IOException

      Writes a minimal entry to represent an empty matrix on hdfs.
      Parameters:
        `fname` - file name
        `rlen` - number of rows
        `clen` - number of columns
        `blen` - number of rows/cols in block
      Throws:
        `IOException` - if IOException occurs

    - #### createMatrixBlocksForReuse

          public static MatrixBlock[] createMatrixBlocksForReuse(long rlen,
                                                                 long clen,
                                                                 int blen,
                                                                 boolean sparse,
                                                                 long nonZeros)

    - #### getMatrixBlockForReuse

          public static MatrixBlock getMatrixBlockForReuse(MatrixBlock[] blocks,
                                                           int rows,
                                                           int cols,
                                                           int blen)

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