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

Interface Summary
AOffsetsGroup
ColGroupIO: IO for ColGroups, it enables read and write ColGroups
ColGroupSizes
ColGroupUtils
IContainADictionary
IContainDefaultTuple
IFrameOfReferenceGroup: Interface for frame of reference groups.
IMapToDataGroup

Class Summary
AColGroup: Abstract Class that is the lowest class type for the Compression framework.
AColGroupCompressed: Base class for column groups encoded Encoded in a compressed manner.
AColGroupOffset: Base class for column groups encoded with various types of bitmap encoding.
AColGroupValue
ADictBasedColGroup
AMorphingMMColGroup: Abstract class for column group types that do not perform matrix Multiplication, and decompression for performance reasons but instead transforms into another type of column group type to perform that operation.
APreAgg: Abstract class for all the column groups that use preAggregation for Left matrix multiplications.
ASDC: Column group that sparsely encodes the dictionary values.
ASDCZero
ColGroupConst
ColGroupDDC: Class to encapsulate information about a column group that is encoded with dense dictionary encoding (DDC).
ColGroupDDCFOR: Class to encapsulate information about a column group that is encoded with dense dictionary encoding (DDC).
ColGroupDeltaDDC: Class to encapsulate information about a column group that is first delta encoded then encoded with dense dictionary encoding (DeltaDDC).
ColGroupEmpty
ColGroupFactory: Factory class for constructing ColGroups.
ColGroupLinearFunctional
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.
ColGroupSDC: Column group that sparsely encodes the dictionary values.
ColGroupSDCFOR: ColGroup for Patched Frame Of Reference.
ColGroupSDCSingle: Column group that sparsely encodes the dictionary values.
ColGroupSDCSingleZeros: Column group that sparsely encodes the dictionary values.
ColGroupSDCZeros: Column group that sparsely encodes the dictionary values.
ColGroupUncompressed: Column group type for columns that are stored as dense arrays of doubles.

Enum Summary
AColGroup.CompressionType: Public super types of compression ColGroups supported