# Package org.apache.sysds.runtime.compress.colgroup

- Class Summary
  Class | Description
  --- | ---
  ADictionary | This dictionary class aims to encapsulate the storage and operations over unique floating point values of a column group.
  ColGroup | Class that stores information about a column group within a compressed matrix block.
  ColGroupConverter | Utility functions for ColGroup to convert ColGroups or MatrixBlocks.
  ColGroupDDC | Class to encapsulate information about a column group that is encoded with dense dictionary encoding (DDC).
  ColGroupDDC1 | Class to encapsulate information about a column group that is encoded with dense dictionary encoding (DDC) using 1 byte codes.
  ColGroupDDC2 | Class to encapsulate information about a column group that is encoded with dense dictionary encoding (DDC) using 2 byte codes.
  ColGroupFactory | Factory pattern for constructing ColGroups.
  ColGroupIO | This has the IO responsibility of ColGroups, such that it enables to read and write ColGroups to and from a DataInput and DataOutput
  ColGroupOffset | Base class for column groups encoded with various types of bitmap encoding.
  ColGroupOLE | Class to encapsulate information about a column group that is encoded with simple lists of offsets for each set of distinct values.
  ColGroupRLE | A group of columns compressed with a single run-length encoded bitmap.
  ColGroupSizes |
  ColGroupUncompressed | Column group type for columns that are stored as dense arrays of doubles.
  ColGroupValue | Base class for column groups encoded with value dictionary.
  DenseRowIterator |
  Dictionary | This dictionary class aims to encapsulate the storage and operations over unique floating point values of a column group.
  QDictionary | This dictionary class aims to encapsulate the storage and operations over unique floating point values of a column group.
  SparseRowIterator |

- Enum Summary
  Enum | Description
  --- | ---
  ColGroup.CompressionType | Public Group types supported Note For instance DDC is called DDC not DDC1, or DDC2 which is a specific subtype of the DDC.

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