Package tech.tablesaw.table

Class Projection

java.lang.Object

tech.tablesaw.table.Relation

tech.tablesaw.table.Projection

public class Projection
extends Relation

A table projection, i.e. the subset of columns in a table that should be returned in a query

Constructor Summary

Constructors

Constructor	Description
Projection(Table table, String[] columnNames)

Method Summary

Modifier and Type	Method	Description
Relation	addColumns(Column... cols)
void	clear()	Clears all the dat in the relation, leaving the structure intact
Column	column(int columnIndex)	Returns the column at columnIndex (0-based)
int	columnCount()	Returns the number of columns in the relation
int	columnIndex(Column col)	Returns the index of the given column
List<String>	columnNames()
List<Column>	columns()	Returns a list of all the columns in the relation
Table	first(int nRows)
String	get(int r, int c)	Returns a String representing the value found at column index c and row index r
String	name()	Returns the name of this relation
Relation	removeColumns(Column... columns)	Removes the given columns from the receiver
int	rowCount()	Returns the number of rows in the relation
Relation	setName(String name)
Table	where(Filter filter)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from class tech.tablesaw.table.Relation

asMatrix, booleanColumn, booleanColumn, booleanColumns, categoricalColumn, categoricalColumn, column, columnIndex, columnsOfType, columnTypes, colWidths, containsColumn, dateColumn, dateColumn, dateColumns, dateTimeColumn, dateTimeColumn, dateTimeColumns, getUnformatted, isEmpty, nCol, nCol, numberColumn, numberColumn, numberColumns, print, print, printAll, removeColumns, removeColumns, shape, stringColumn, stringColumn, stringColumns, structure, summary, timeColumn, timeColumn, timeColumns, toString

Constructor Detail

Projection

public Projection(Table table,
                  String[] columnNames)

Method Detail

where

public Table where(Filter filter)

addColumns

public Relation addColumns(Column... cols)

Specified by:

addColumns in class Relation

setName

public Relation setName(String name)

Specified by:

setName in class Relation

removeColumns

public Relation removeColumns(Column... columns)

Description copied from class: Relation

Removes the given columns from the receiver

Specified by:

removeColumns in class Relation

first

public Table first(int nRows)

Specified by:

first in class Relation

column

public Column column(int columnIndex)

Description copied from class: Relation

Returns the column at columnIndex (0-based)

Specified by:

column in class Relation

Parameters:

columnIndex - an integer at least 0 and less than number of columns in the relation

Returns:

the column at the given index

columnCount

public int columnCount()

Description copied from class: Relation

Returns the number of columns in the relation

Specified by:

columnCount in class Relation

rowCount

public int rowCount()

Description copied from class: Relation

Returns the number of rows in the relation

Specified by:

rowCount in class Relation

columns

public List<Column> columns()

Description copied from class: Relation

Returns a list of all the columns in the relation

Specified by:

columns in class Relation

columnIndex

public int columnIndex(Column col)

Description copied from class: Relation

Returns the index of the given column

Specified by:

columnIndex in class Relation

get

public String get(int r,
                  int c)

Description copied from class: Relation

Returns a String representing the value found at column index c and row index r

Specified by:

get in class Relation

name

public String name()

Description copied from class: Relation

Returns the name of this relation

Specified by:

name in class Relation

clear

public void clear()

Description copied from class: Relation

Clears all the dat in the relation, leaving the structure intact

Specified by:

clear in class Relation

columnNames

public List<String> columnNames()

Specified by:

columnNames in class Relation