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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 DataCell s 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 DataCell s
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 DataCell s, 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 | DataTableSpec s 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. |
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 DataRow
s, that allow
access to all DataCell
s 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
.
DataCell
s 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 DataCell
s 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.
DataTable
s could be arbitrary big, thus
they shouldn't be copied or held in memory.
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