tech.tablesaw.store

Class StorageManager

java.lang.Object

tech.tablesaw.store.StorageManager

public class StorageManager
extends Object

A controller for reading and writing data in Tablesaw's own compressed, column-oriented file format

Constructor Summary

Constructors

Constructor and Description
StorageManager()

Method Summary

Modifier and Type	Method and Description
static CategoryColumn	readCategoryColumn(String fileName, ColumnMetadata metadata)
static Table	readTable(String path) Reads a tablesaw table into memory
static String	saveTable(String folderName, Relation table) Saves the data from the given table in the location specified by folderName.
static void	writeColumn(String fileName, BooleanColumn column)
static void	writeColumn(String fileName, CategoryColumn column) Writes out the values of the category column encoded as ints to minimize the time required for subsequent reads
static void	writeColumn(String fileName, DateColumn column)
static void	writeColumn(String fileName, DateTimeColumn column)
static void	writeColumn(String fileName, DoubleColumn column)
static void	writeColumn(String fileName, FloatColumn column)
static void	writeColumn(String fileName, IntColumn column)
static void	writeColumn(String fileName, LongColumn column)
static void	writeColumn(String fileName, ShortColumn column)
static void	writeColumn(String fileName, TimeColumn column)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StorageManager

public StorageManager()

Method Detail

readTable

public static Table readTable(String path)
                       throws IOException

Reads a tablesaw table into memory

Parameters:

path - The location of the table. It is interpreted as relative to the working directory if not fully specified. The path will typically end in ".saw", as in "mytables/nasdaq-2015.saw"

Throws:

IOException - if the file cannot be read

readCategoryColumn

public static CategoryColumn readCategoryColumn(String fileName,
                                                ColumnMetadata metadata)
                                         throws IOException

Throws:

IOException

saveTable

public static String saveTable(String folderName,
                               Relation table)
                        throws IOException

Saves the data from the given table in the location specified by folderName. Within that folder each table has its own sub-folder, whose name is based on the name of the table.

NOTE: If you store a table with the same name in the same folder. The data in that folder will be over-written.

The storage format is the tablesaw compressed column-oriented format, which consists of a set of file in a folder. The name of the folder is based on the name of the table.

Parameters:

folderName - The location of the table (for example: "mytables")

table - The table to be saved

Returns:

The path and name of the table

Throws:

IOException - IOException if the file can not be read

writeColumn

public static void writeColumn(String fileName,
                               FloatColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               DoubleColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               CategoryColumn column)
                        throws IOException

Writes out the values of the category column encoded as ints to minimize the time required for subsequent reads

The files are written Strings first, then the ints that encode them so they can be read in the opposite order

Throws:

IOException - IOException if the file can not be read

writeColumn

public static void writeColumn(String fileName,
                               IntColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               ShortColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               LongColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               DateColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               DateTimeColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               TimeColumn column)
                        throws IOException

Throws:

IOException

writeColumn

public static void writeColumn(String fileName,
                               BooleanColumn column)
                        throws IOException

Throws:

IOException