Package uk.ac.starlink.ttools.filter
Class JELColumnSupplement
- java.lang.Object
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- uk.ac.starlink.ttools.filter.JELColumnSupplement
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- 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
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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.
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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.
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Constructor Detail
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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 contextexprs
- JEL expressions for columnscolInfos
- 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
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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 contextexpr
- JEL expression for columncolInfo
- metadata for column (data type may be changed to match expression output); if null, name is generated automatically- Throws:
java.io.IOException
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Method Detail
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getColumnCount
public int getColumnCount()
Description copied from interface:ColumnSupplement
Returns the number of columns defined by this object.- Specified by:
getColumnCount
in interfaceColumnSupplement
- Returns:
- number of columns
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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 interfaceColumnSupplement
- Parameters:
icol
- column index within this object- Returns:
- column metadata for the icol'th column defined by this object
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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 interfaceColumnSupplement
- Parameters:
irow
- row indexicol
- column index- Returns:
- cell content
- Throws:
java.io.IOException
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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 interfaceColumnSupplement
- Parameters:
irow
- row index- Returns:
- array of cell contents for all the cells in this row
- Throws:
java.io.IOException
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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 interfaceColumnSupplement
- Parameters:
rseq
- row sequence providing data from the host table- Returns:
- iterator over row data from supplementary columns
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