Package uk.ac.starlink.table
Class JoinStarTable
java.lang.Object
uk.ac.starlink.table.AbstractStarTable
uk.ac.starlink.table.JoinStarTable
- All Implemented Interfaces:
Closeable
,AutoCloseable
,StarTable
Joins a number of tables to produce a single combined table.
The result consists of all the constituent tables side by side,
so has a number of columns equal to the sum of the numbers of columns
in all the constituent tables.
The nth row of this table is composed by appending the
nth rows of all the constituent tables together in sequence.
The number of rows is equal to the
smallest of all the number of rows in the constituent tables
(typically they will all have the same number of rows).
Random access is only available if it is available in all the
constituent tables.
While this table is active, the columns that the constituent tables had at the time of its construction shouldn't change their characteristics in incompatible ways or disappear. It's OK to add new columns though.
- Author:
- Mark Taylor (Starlink)
-
Constructor Summary
ConstructorsConstructorDescriptionJoinStarTable
(StarTable[] tables) Constructs a new JoinStarTable from a list of constituent tables.JoinStarTable
(StarTable[] tables, JoinFixAction[] fixCols) Constructs a new JoinStarTable from a list of constituent tables, optionally renaming duplicated column names. -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Closes all the constituent tables.getCell
(long irow, int icol) TheAbstractStarTable
implementation of this method throws anUnsupportedOperationException
, since unless otherwise provided there is no random access.int
Returns the number of columns in this table.getColumnInfo
(int icol) Returns the object describing the data in a given column.Object[]
getRow
(long irow) TheAbstractStarTable
implementation of this method constructs a row by repeated invocation ofAbstractStarTable.getCell(long, int)
.Returns an object which can provide random access to this table's data, if random access is implemented.long
Returns the number of rows in this table, if known.Returns an object which can iterate over all the rows in the table sequentially.Returns an unmodifiable list of the constituent tables providing the base data for this join table.boolean
isRandom()
TheAbstractStarTable
implementation of this method returnsfalse
.Methods inherited from class uk.ac.starlink.table.AbstractStarTable
checkedLongToInt, getColumnAuxDataInfos, getName, getParameters, getRowSplittable, getURL, setName, setParameters, setURL
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface uk.ac.starlink.table.StarTable
getParameterByName, setParameter
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Constructor Details
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JoinStarTable
Constructs a new JoinStarTable from a list of constituent tables, optionally renaming duplicated column names.- Parameters:
tables
- array of constituent table objects providing the data and metadata for a new joined tablefixCols
- actions to be taken in modifying column names from the originals (may be null for no action)
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JoinStarTable
Constructs a new JoinStarTable from a list of constituent tables. No column renaming is done.- Parameters:
tables
- array of constituent table objects providing the data and metadata for a new joined table
-
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Method Details
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getTables
Returns an unmodifiable list of the constituent tables providing the base data for this join table.- Returns:
- list of tables
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getColumnCount
public int getColumnCount()Description copied from interface:StarTable
Returns the number of columns in this table.- Specified by:
getColumnCount
in interfaceStarTable
- Specified by:
getColumnCount
in classAbstractStarTable
- Returns:
- the number of columns
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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
- Specified by:
getRowCount
in classAbstractStarTable
- Returns:
- the number of rows, or -1
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getColumnInfo
Description copied from interface:StarTable
Returns the object describing the data in a given column.- Specified by:
getColumnInfo
in interfaceStarTable
- Specified by:
getColumnInfo
in classAbstractStarTable
- Parameters:
icol
- the column for which header information is required- Returns:
- a ValueInfo object for column
icol
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isRandom
public boolean isRandom()Description copied from class:AbstractStarTable
TheAbstractStarTable
implementation of this method returnsfalse
.- Specified by:
isRandom
in interfaceStarTable
- Overrides:
isRandom
in classAbstractStarTable
- Returns:
true
if table random access methods are available
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getCell
Description copied from class:AbstractStarTable
TheAbstractStarTable
implementation of this method throws anUnsupportedOperationException
, since unless otherwise provided there is no random access.- Specified by:
getCell
in interfaceStarTable
- Overrides:
getCell
in classAbstractStarTable
- Parameters:
irow
- the index of the cell's rowicol
- the index of the cell's column- Returns:
- the contents of this cell
- Throws:
IOException
- if there is an error reading the data
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getRow
Description copied from class:AbstractStarTable
TheAbstractStarTable
implementation of this method constructs a row by repeated invocation ofAbstractStarTable.getCell(long, int)
.- Specified by:
getRow
in interfaceStarTable
- Overrides:
getRow
in classAbstractStarTable
- Parameters:
irow
- the index of the row to retrieve- Returns:
- an array of the objects in each cell in row
irow
- Throws:
IOException
- if there is an error reading the data
-
getRowSequence
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
- Specified by:
getRowSequence
in classAbstractStarTable
- Returns:
- new RowSequence
- Throws:
IOException
- if there is an error providing access
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getRowAccess
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 classAbstractStarTable
- Returns:
- new RowAccess
- Throws:
IOException
- if there is an error setting up access
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close
Closes all the constituent tables.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in interfaceStarTable
- Overrides:
close
in classAbstractStarTable
- Throws:
IOException
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