Class RowPermutedStarTable
- java.lang.Object
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- uk.ac.starlink.table.WrapperStarTable
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- uk.ac.starlink.table.RowPermutedStarTable
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
,StarTable
public class RowPermutedStarTable extends WrapperStarTable
Wrapper table which provides a view of a base table in which the rows are permuted. Each row in the wrapper table is a view of one in the base table. It is permitted for the wrapper to contain multiple views of the same column in the base.A
long[]
array,rowMap
, is used to keep track of which rows in this table correspond to which rows in the base table; the n'th row in this table corresponds to the rowMap[n]'th row in the base table. The rowMap array may contain duplicate entries, but should not contain any entries larger than the number of rows in the base table. Any negative entry is treated as a special case resulting in a 'blank' row of all null values. It can be modified during the life of the table, but it's not a good idea to do this while a RowSequence is active.- Author:
- Mark Taylor (Starlink)
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Field Summary
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Fields inherited from class uk.ac.starlink.table.WrapperStarTable
baseTable
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Constructor Summary
Constructors Constructor Description RowPermutedStarTable(StarTable baseTable)
Constructs a new RowPermutedTable with rows initially in unpermuted order.RowPermutedStarTable(StarTable baseTable, long[] rowMap)
Constructs a new RowPermutedStarTable from a base table and a rowMap array.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.Object
getCell(long irow, int icol)
Returns the contents of a given table cell.java.lang.Object[]
getRow(long irow)
Returns the contents of a given table row.RowAccess
getRowAccess()
Returns an object which can provide random access to this table's data, if random access is implemented.long
getRowCount()
Returns the number of rows in this table, if known.long[]
getRowMap()
Returns the mapping array.RowSequence
getRowSequence()
Returns an object which can iterate over all the rows in the table sequentially.RowSplittable
getRowSplittable()
Returns an object which can iterate over all the rows in the table, but which may also be requested to split recursively for potentially parallel processing.boolean
isRandom()
Returns true.void
setRowMap(long[] rowMap)
Sets the mapping array.-
Methods inherited from class uk.ac.starlink.table.WrapperStarTable
checkedLongToInt, close, getBaseTable, getColumnAuxDataInfos, getColumnCount, getColumnInfo, getName, getParameterByName, getParameters, getURL, setName, setParameter, setURL, toString
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Constructor Detail
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RowPermutedStarTable
public RowPermutedStarTable(StarTable baseTable, long[] rowMap)
Constructs a new RowPermutedStarTable from a base table and a rowMap array.baseTable must provide random access.
- Parameters:
baseTable
- base tablerowMap
- array mapping rows in the new permuted table to rows in baseTable- Throws:
java.lang.IllegalArgumentException
- if baseTable.isRandom returns false
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RowPermutedStarTable
public RowPermutedStarTable(StarTable baseTable)
Constructs a new RowPermutedTable with rows initially in unpermuted order.- Parameters:
baseTable
- base table
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Method Detail
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getRowMap
public long[] getRowMap()
Returns the mapping array.- Returns:
- array mapping rows in this table to rows in the base table
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setRowMap
public void setRowMap(long[] rowMap)
Sets the mapping array.- Parameters:
rowMap
- array mapping rows in this table to rows in the base table
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getRowCount
public long getRowCount()
Description copied from interface:StarTable
Returns the number of rows in this table, if known. If the number of rows cannot be (easily) determined, a value of -1 will be returned.- Specified by:
getRowCount
in interfaceStarTable
- Overrides:
getRowCount
in classWrapperStarTable
- Returns:
- the number of rows, or -1
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isRandom
public boolean isRandom()
Returns true.- Specified by:
isRandom
in interfaceStarTable
- Overrides:
isRandom
in classWrapperStarTable
- Returns:
- true if table random access methods are available
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getRowAccess
public RowAccess getRowAccess() throws java.io.IOException
Description copied from interface:StarTable
Returns an object which can provide random access to this table's data, if random access is implemented. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.- Specified by:
getRowAccess
in interfaceStarTable
- Overrides:
getRowAccess
in classWrapperStarTable
- Returns:
- new RowAccess
- Throws:
java.io.IOException
- if there is an error setting up access
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getRowSequence
public RowSequence getRowSequence() throws java.io.IOException
Description copied from interface:StarTable
Returns an object which can iterate over all the rows in the table sequentially. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.- Specified by:
getRowSequence
in interfaceStarTable
- Overrides:
getRowSequence
in classWrapperStarTable
- Returns:
- new RowSequence
- Throws:
java.io.IOException
- if there is an error providing access
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getRowSplittable
public RowSplittable getRowSplittable() throws java.io.IOException
Description copied from interface:StarTable
Returns an object which can iterate over all the rows in the table, but which may also be requested to split recursively for potentially parallel processing.The return value must be non-null, and may provide splitting arrangements specially appropriate for the implementation. If this table 'wraps' an upstream table, it is usually best to base the implementation on calls to the the upstream
getRowSplittable
method, so that upstream policy about how to divide up the table is respected. However, implementations without special requirements may returnTables.getDefaultRowSplittable
(this)
.- Specified by:
getRowSplittable
in interfaceStarTable
- Overrides:
getRowSplittable
in classWrapperStarTable
- Returns:
- new RowSplittable
- Throws:
java.io.IOException
- See Also:
RowRunner
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getCell
public java.lang.Object getCell(long irow, int icol) throws java.io.IOException
Description copied from interface:StarTable
Returns the contents of a given table cell. The class of the returned object should be the same as, or a subclass of, the class returned by getColumnInfo(icol).getContentClass().This method is safe for concurrent use from multiple threads, but in general it is recommended to use a
RowAccess
instead.- Specified by:
getCell
in interfaceStarTable
- Overrides:
getCell
in classWrapperStarTable
- Parameters:
irow
- the index of the cell's rowicol
- the index of the cell's column- Returns:
- the contents of this cell
- Throws:
java.io.IOException
- if there is an error reading the data
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getRow
public java.lang.Object[] getRow(long irow) throws java.io.IOException
Description copied from interface:StarTable
Returns the contents of a given table row. The returned value is equivalent to an array formed of all the objects returned by getCell(irow,icol) for all the columns icol in sequence.This method is safe for concurrent use from multiple threads, but in general it is recommended to use a
RowAccess
instead.- Specified by:
getRow
in interfaceStarTable
- Overrides:
getRow
in classWrapperStarTable
- Parameters:
irow
- the index of the row to retrieve- Returns:
- an array of the objects in each cell in row irow
- Throws:
java.io.IOException
- if there is an error reading the data
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