Package org.knime.core.data

Contains the interface definitions of the DataCell and DataTable and related classes, used to store and access the actual data.

See:
          Description

Interface Summary
BoundedValue A DataCell should implement this interface to indicate that its objects can be reasonably ordered.
ComplexNumberValue Interface supporting generic complex number values.
DataCellDataInput Extended DataInput, which enables de-serialization of DataCell objects.
DataCellDataOutput Extended DataOutput, which also allows the serialization of DataCell objects.
DataCellSerializer<T extends DataCell> Interface for classes that can read or write specific DataCell implementations.
DataRow Container interface for a vector of DataCells and a row key for unique identification.
DataTable Most general data interface in table structure with a fixed number of columns and iterable rows (no random access).
DataValue The interface all value interfaces of DataCells are derived from.
DoubleValue Interface supporting generic double values.
FuzzyIntervalValue Interface supporting fuzzy interval cells holding support and core min and max values.
FuzzyNumberValue Interface supporting fuzzy numbers defined by min and max support, and core.
IntervalValue Interface supporting interval cells holding minimum and maximum boundaries.
IntValue Interface supporting generic int values.
LongValue Interface supporting generic long values.
NominalValue Interface of a StringCell, which does not enforce additional functionality but indicates that cells implementing this value can be used as nominal values.
StringValue Interface of a StringCell, forces method to return string value.
TimestampValue Deprecated. Date and time in KNIME is represented by DateAndTimeValue and DateAndTimeCell.
 

Class Summary
ComplexNumberValue.ComplexNumberUtilityFactory Meta information to the complex number value.
ComplexNumberValueComparator Comparator returned by the ComplexNumberValue.
DataCell Abstract base class of all DataCells, which acts as a container for arbitrary values and defines the common abilities all cells must provide, that is: retrieve the cell type, a string representation of the value, find out if this cell is missing, and test whether it is equal to another one.
DataColumnDomain Final DataColumnDomain object holding meta infos about one column, that are, possible values and/or upper and lower bounds - if available.
DataColumnDomainCreator A column domain creator is used to initialize possible values and lower and upper bounds using DataCell objects.
DataColumnProperties Property map that contains annotations assigned to a column.
DataColumnSpec A DataColumnSpec describes one column in a DataTable.
DataColumnSpecCreator A factory class to create a DataColumnSpec (as the only way from outside this package).
DataTableSpec DataTableSpecs specify the structure of a DataTable.
DataType Type description associated with a certain implementation of a DataCell.
DataValue.UtilityFactory Implementation of the meta information to a DataValue.
DataValueComparator The comparator used to compare two DataValue objects.
DoubleValue.DoubleUtilityFactory Implementations of the meta information of this value class.
DoubleValueComparator Comparator returned by the DoubleValue interface.
FuzzyIntervalValue.FuzzyIntervalUtilityFactory Implementations of the meta information of this value class.
FuzzyIntervalValueComparator Comparator returned by the FuzzyIntervalValue datacell type.
FuzzyNumberValue.FuzzyNumberUtilityFactory Implementations of the meta information of this value class.
FuzzyNumberValueComparator Comparator returned by the FuzzyNumberValue datacell type.
IntervalValue.IntervalUtilityFactory Implementations of the meta information of this value class.
IntervalValueComparator Comparator returned by the IntervalValue datacell type.
IntValue.IntUtilityFactory Implementations of the meta information of this value class.
IntValueComparator Comparator returned by the IntValue interface.
LongValue.LongUtilityFactory Implementations of the meta information of this value class.
LongValueComparator Comparator returned by the LongValue interface.
RowIterator Classes extending this class iterate over the rows of a DataTable.
RowKey Key for a specific row which holds an identifier of type String.
StringValue.StringUtilityFactory Implementations of the meta information of this value class.
StringValueComparator Comparator returned by the StringValue interface.
TimestampValue.TimestampUtilityFactory Implementations of the meta information of this value class.
TimestampValue.TimestampValueComparator Comparator returned by the TimestampValue interface.
 

Package org.knime.core.data Description

Contains the interface definitions of the DataCell and DataTable and related classes, used to store and access the actual data.

A DataTable is used to pass data along between nodes in the workflow.

It has rows and columns. The number of columns is fixed. The type of data stored in each column is well defined, and each column has a unique name. Each row consists of a certain number of cells (which contain the actual data) and a unique row identifier. The data in a DataTable is read-only.

A DataTable contains a DataTableSpec object which describes the structure of the table (the number of columns, the column types, etc.) and a RowIterator which allows to iterate over the rows of the table and actually access the data.

The iterator returns DataRows, that allow access to all DataCells in this row by index (the index of the column). The number of rows is usually not known in advance (not in all tables), the iterator indicates when it reaches the end of the table. As the source underlying the table could be sequential and of arbitrary size, the general DataTable interface doesn't provide any random access methods.

The DataTableSpec contains the meta information of the data table. It can be used to query the columns' name and type, and the number of columns. In addition to that it is also used to pass information along to connected successors to let them know of the structure of the table to come. So, if the successor's preparations for execution (like the settings) depend on the structure of the data table of the predecessor, it can be set up after it received the DataTableSpec.

Accessing the data in a DataTable

DataCells are of certain type, depending on the type of data appearing in the corresponding column. For each data cell type certain objects exist describing the cell's properties, capabilities and compatibilities. This is the DataCell derivative implementing DataValue, which defines how to access the value stored in the data cell.

Read more on data cells here and in the FAQ.

Default implementations of DataCells can be found in the org.knime.core.data.def package. These implementations store the value of the cell in a member of the corresponding Java data type.

DataTables could be arbitrary big, thus they shouldn't be copied or held in memory.



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University of Konstanz, Germany.
Chair for Bioinformatics and Information Mining, Prof. Dr. Michael R. Berthold.
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