JELColumnSupplement (Starjava TTOOLS API)

java.lang.Object
- uk.ac.starlink.ttools.filter.JELColumnSupplement

All Implemented Interfaces:

ColumnSupplement
```
public class JELColumnSupplement
extends java.lang.Object
implements ColumnSupplement
```
ColumnSupplement that generates new columns based on JEL expressions.

Since:

27 Mar 2012

Author:

Mark Taylor

Constructor Summary

Constructors
Constructor	Description
`JELColumnSupplement(uk.ac.starlink.table.StarTable inTable, java.lang.String[] exprs, uk.ac.starlink.table.ColumnInfo[] colInfos)`	Constructs a multiple-column JEL column supplement.
`JELColumnSupplement(uk.ac.starlink.table.StarTable inTable, java.lang.String expr, uk.ac.starlink.table.ColumnInfo colInfo)`	Constructs a single-column JEL column supplement.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`SupplementSequence`	`createSequence(uk.ac.starlink.table.RowSequence rseq)`	Returns a new iterator over the values in the columns defined by this object.
`java.lang.Object`	`getCell(long irow, int icol)`	Random access read of a cell defined by this object.
`int`	`getColumnCount()`	Returns the number of columns defined by this object.
`uk.ac.starlink.table.ColumnInfo`	`getColumnInfo(int icol)`	Returns the column metadata object for a given column.
`java.lang.Object[]`	`getRow(long irow)`	Random access read of a row defined by this object.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - JELColumnSupplement
```
public JELColumnSupplement(uk.ac.starlink.table.StarTable inTable,
                           java.lang.String[] exprs,
                           uk.ac.starlink.table.ColumnInfo[] colInfos)
                    throws java.io.IOException
```
    Constructs a multiple-column JEL column supplement.
    
    Parameters:
    
    inTable - table providing JEL context
    
    exprs - JEL expressions for columns
    
    colInfos - metadata for columns (data types may be changed to match expression output); if null, names are generated automatically
    
    Throws:
    
    java.io.IOException - with a helpful message if one of the expressions cannot be compiled
  - JELColumnSupplement
```
public JELColumnSupplement(uk.ac.starlink.table.StarTable inTable,
                           java.lang.String expr,
                           uk.ac.starlink.table.ColumnInfo colInfo)
                    throws java.io.IOException
```
    Constructs a single-column JEL column supplement.
    
    Parameters:
    
    inTable - table providing JEL context
    
    expr - JEL expression for column
    
    colInfo - metadata for column (data type may be changed to match expression output); if null, name is generated automatically
    
    Throws:
    
    java.io.IOException
- Method Detail
  - getColumnCount
```
public int getColumnCount()
```
    Description copied from interface: ColumnSupplement
    
    Returns the number of columns defined by this object.
    
    Specified by:
    
    getColumnCount in interface ColumnSupplement
    
    Returns:
    
    number of columns
  - getColumnInfo
```
public uk.ac.starlink.table.ColumnInfo getColumnInfo(int icol)
```
    Description copied from interface: ColumnSupplement
    
    Returns the column metadata object for a given column.
    
    Specified by:
    
    getColumnInfo in interface ColumnSupplement
    
    Parameters:
    
    icol - column index within this object
    
    Returns:
    
    column metadata for the icol'th column defined by this object
  - getCell
```
public java.lang.Object getCell(long irow,
                                int icol)
                         throws java.io.IOException
```
    Description copied from interface: ColumnSupplement
    
    Random access read of a cell defined by this object.
    
    Specified by:
    
    getCell in interface ColumnSupplement
    
    Parameters:
    
    irow - row index
    
    icol - column index
    
    Returns:
    
    cell content
    
    Throws:
    
    java.io.IOException
  - getRow
```
public java.lang.Object[] getRow(long irow)
                          throws java.io.IOException
```
    Description copied from interface: ColumnSupplement
    
    Random access read of a row defined by this object.
    
    Specified by:
    
    getRow in interface ColumnSupplement
    
    Parameters:
    
    irow - row index
    
    Returns:
    
    array of cell contents for all the cells in this row
    
    Throws:
    
    java.io.IOException
  - createSequence
```
public SupplementSequence createSequence(uk.ac.starlink.table.RowSequence rseq)
```
    Description copied from interface: ColumnSupplement
    
    Returns a new iterator over the values in the columns defined by this object. The supplied row sequence must be from an appropriate host table; if not, behaviour is undefined.
    
    Specified by:
    
    createSequence in interface ColumnSupplement
    
    Parameters:
    
    rseq - row sequence providing data from the host table
    
    Returns:
    
    iterator over row data from supplementary columns

Class JELColumnSupplement

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

JELColumnSupplement

JELColumnSupplement

Method Detail

getColumnCount

getColumnInfo

getCell

getRow

createSequence