Package nom.tam.util
Class ColumnTable<T>
- java.lang.Object
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- nom.tam.util.ColumnTable<T>
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- All Implemented Interfaces:
DataTable
public class ColumnTable<T> extends java.lang.Object implements DataTable
A data table is conventionally considered to consist of rows and columns, where the structure within each column is constant, but different columns may have different structures. I.e., structurally columns may differ but rows are identical. Typically tabular data is usually stored in row order which can make it extremely difficult to access efficiently using Java. This class provides efficient access to data which is stored in row order and allows users to get and set the elements of the table. The table can consist only of arrays of primitive types. Data stored in column order can be efficiently read and written using the BufferedDataXputStream classes. The table is represented entirely as a set of one-dimensional primitive arrays. For a given column, a row consists of some number of contiguous elements of the array. Each column is required to have the same number of rows. Information regarding the dimensionality of columns and possible data pointers is retained for use by clients which can understand them.
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Constructor Summary
Constructors Constructor Description ColumnTable(java.lang.Object[] arrays, int[] sizes)
Create the object after checking consistency.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addColumn(java.lang.Object newColumn, int size)
Add a column .protected void
addPointer(java.lang.Object data)
Add a pointer in the pointer lists.void
addRow(java.lang.Object[] row)
Add a row to the table.protected void
checkArrayConsistency(java.lang.Object[] newArrays, int[] newSizes)
Check that the columns and sizes are consistent.ColumnTable<T>
copy()
void
deleteColumns(int start, int len)
Delete a contiguous set of columns from the table.void
deleteRow(int row)
Delete a row from the table.void
deleteRows(int row, int length)
Delete a contiguous set of rows from the table.java.lang.Class<?>[]
getBases()
Get the base classes of the columns.java.lang.Object
getColumn(int col)
Get a particular column.java.lang.Object[]
getColumns()
java.lang.Object
getElement(int row, int col)
Get a element of the table.T
getExtraState()
int
getNCols()
Get the number of columns in the table.int
getNRows()
Get the number of rows in the table.java.lang.Object
getRow(int row)
Get a row of data.int[]
getSizes()
char[]
getTypes()
Get the characters describing the base classes of the columns.protected void
initializePointers()
Set the pointer arrays for the eight primitive types to point to the appropriate elements of arrays.void
read(ArrayDataInput is)
Read a table.void
read(ArrayDataInput is, int rowStart, int rowEnd, int columnNr)
Read a column of a table.void
setColumn(int col, java.lang.Object newColumn)
Set the values in a particular column.void
setElement(int row, int col, java.lang.Object x)
Modify an element of the table.void
setExtraState(T opaque)
Store additional information that may be needed by the client to regenerate initial arrays.void
setRow(int row, java.lang.Object x)
Modify a row of data.void
write(ArrayDataOutput os)
Write a table.void
write(ArrayDataOutput os, int rowStart, int rowEnd, int columnNr)
Write a column of a table.
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Constructor Detail
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ColumnTable
public ColumnTable(java.lang.Object[] arrays, int[] sizes) throws TableException
Create the object after checking consistency.- Parameters:
arrays
- An array of one-d primitive arrays.sizes
- The number of elements in each row for the corresponding column- Throws:
TableException
- if the structure of the columns is not consistent
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Method Detail
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addColumn
public void addColumn(java.lang.Object newColumn, int size) throws TableException
Add a column .- Parameters:
newColumn
- the column to add.size
- size for the column- Throws:
TableException
- if the structure of the new column does not fit the structure of the rows/columns
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addPointer
protected void addPointer(java.lang.Object data) throws TableException
Add a pointer in the pointer lists.- Parameters:
data
- data pointer to add- Throws:
TableException
- if the structure of the specified array does not fit the structure of the rows/columns
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addRow
public void addRow(java.lang.Object[] row) throws TableException
Add a row to the table. This method is very inefficient for adding multiple rows and should be avoided if possible.- Parameters:
row
- the row to add- Throws:
TableException
- if the structure of the specified array does not fit the structure of the rows/columns
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checkArrayConsistency
protected void checkArrayConsistency(java.lang.Object[] newArrays, int[] newSizes) throws TableException
Check that the columns and sizes are consistent. Inconsistencies include:- arrays and sizes have different lengths.
- an element of arrays is not a primitive array.
- the size of an array is not divisible by the sizes entry.
- the number of rows differs for the columns.
- Parameters:
newArrays
- The arrays defining the columns.newSizes
- The number of elements in each row for the column.- Throws:
TableException
- if the table was inconsistent
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copy
public ColumnTable<T> copy() throws TableException
- Throws:
TableException
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deleteColumns
public void deleteColumns(int start, int len) throws TableException
Delete a contiguous set of columns from the table.- Parameters:
start
- The first column (0-indexed) to be deleted.len
- The number of columns to be deleted.- Throws:
TableException
- if the request goes outside the boundaries of the table or if the length is negative.
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deleteRow
public void deleteRow(int row) throws TableException
Delete a row from the table.- Parameters:
row
- The row (0-indexed) to be deleted.- Throws:
TableException
- if the request goes outside the boundaries of the table or if the length is negative.
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deleteRows
public void deleteRows(int row, int length) throws TableException
Delete a contiguous set of rows from the table.- Parameters:
row
- The row (0-indexed) to be deleted.length
- The number of rows to be deleted.- Throws:
TableException
- if the request goes outside the boundaries of the table or if the length is negative.
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getBases
public java.lang.Class<?>[] getBases()
Get the base classes of the columns.- Returns:
- An array of Class objects, one for each column.
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getColumn
public java.lang.Object getColumn(int col)
Get a particular column.
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getColumns
public java.lang.Object[] getColumns()
- Returns:
- the actual data arrays
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getElement
public java.lang.Object getElement(int row, int col)
Get a element of the table.- Specified by:
getElement
in interfaceDataTable
- Parameters:
row
- The row desired.col
- The column desired.- Returns:
- A primitive array containing the information. Note that an array will be returned even if the element is a scalar.
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getExtraState
public T getExtraState()
- Returns:
- the pointer state
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getNCols
public int getNCols()
Get the number of columns in the table.
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getNRows
public int getNRows()
Get the number of rows in the table.
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getRow
public java.lang.Object getRow(int row)
Get a row of data.
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getSizes
public int[] getSizes()
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getTypes
public char[] getTypes()
Get the characters describing the base classes of the columns.- Returns:
- An array of char's, one for each column.
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initializePointers
protected void initializePointers()
Set the pointer arrays for the eight primitive types to point to the appropriate elements of arrays.
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read
public void read(ArrayDataInput is) throws java.io.IOException
Read a table.- Parameters:
is
- The input stream to read from.- Throws:
java.io.IOException
- if the reading failed
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setColumn
public void setColumn(int col, java.lang.Object newColumn) throws TableException
Set the values in a particular column. The new values must match the old in length but not necessarily in type.- Specified by:
setColumn
in interfaceDataTable
- Parameters:
col
- The column to modify.newColumn
- The new column data. This should be a primitive array.- Throws:
TableException
- Thrown when the new data is not commenserable with information in the table.
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setElement
public void setElement(int row, int col, java.lang.Object x) throws TableException
Modify an element of the table.- Specified by:
setElement
in interfaceDataTable
- Parameters:
row
- The row containing the element.col
- The column containing the element.x
- The new datum. This should be 1-d primitive array.- Throws:
TableException
- Thrown when the new data is not of the same type as the data it replaces.
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setExtraState
public void setExtraState(T opaque)
Store additional information that may be needed by the client to regenerate initial arrays.- Parameters:
opaque
- the extra state to set.
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setRow
public void setRow(int row, java.lang.Object x) throws TableException
Modify a row of data.- Specified by:
setRow
in interfaceDataTable
- Parameters:
row
- The row to be modified.x
- The data to be modified. This should be an array of objects. It is described as an Object here since other table implementations may use other methods to store the data (e.g., @see nom.tam.util.ColumnTable)- Throws:
TableException
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write
public void write(ArrayDataOutput os) throws java.io.IOException
Write a table.- Parameters:
os
- the output stream to write to.- Throws:
java.io.IOException
- if the write operation failed
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write
public void write(ArrayDataOutput os, int rowStart, int rowEnd, int columnNr) throws java.io.IOException
Write a column of a table.- Parameters:
os
- the output stream to write to.rowStart
- first row to writerowEnd
- row number that should not be written anymorecolumnNr
- zero based column number to write.- Throws:
java.io.IOException
- if the write operation failed
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read
public void read(ArrayDataInput is, int rowStart, int rowEnd, int columnNr) throws java.io.IOException
Read a column of a table.- Parameters:
is
- The input stream to read from.rowStart
- first row to readrowEnd
- row number that should not be read anymorecolumnNr
- the columnNumber to read.- Throws:
java.io.IOException
- if the reading failed
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