weka.core.converters

## Class ConverterUtils.DataSource

- java.lang.Object
- - weka.core.converters.ConverterUtils.DataSource

- All Implemented Interfaces:
    java.io.Serializable, RevisionHandler
  Enclosing class:
    ConverterUtils

      public static class ConverterUtils.DataSource
      extends java.lang.Object
      implements java.io.Serializable, RevisionHandler

  Helper class for loading data from files and URLs. Via the ConverterUtils class it determines which converter to use for loading the data into memory. If the chosen converter is an incremental one, then the data will be loaded incrementally, otherwise as batch. In both cases the same interface will be used (`hasMoreElements`, `nextElement`). Before the data can be read again, one has to call the `reset` method. The data source can also be initialized with an Instances object, in order to provide a unified interface to files and already loaded datasets.
  Version:
    $Revision: 14285 $
  Author:
    FracPete (fracpete at waikato dot ac dot nz)
  See Also:
    `hasMoreElements(Instances)`, `nextElement(Instances)`, `reset()`, `ConverterUtils.DataSink`, Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `DataSource(java.io.InputStream stream)` Initializes the datasource with the given input stream.
    `DataSource(Instances inst)` Initializes the datasource with the given dataset.
    `DataSource(Loader loader)` Initializes the datasource with the given Loader.
    `DataSource(java.lang.String location)` Tries to load the data from the file.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Instances` | `getDataSet()` returns the full dataset, can be null in case of an error.
    `Instances` | `getDataSet(int classIndex)` returns the full dataset with the specified class index set, can be null in case of an error.
    `Loader` | `getLoader()` returns the determined loader, null if the DataSource was initialized with data alone and not a file/URL.
    `java.lang.String` | `getRevision()` Returns the revision string.
    `Instances` | `getStructure()` returns the structure of the data.
    `Instances` | `getStructure(int classIndex)` returns the structure of the data, with the defined class index.
    `boolean` | `hasMoreElements(Instances structure)` returns whether there are more Instance objects in the data.
    `static boolean` | `isArff(java.lang.String location)` returns whether the extension of the location is likely to be of ARFF format, i.e., ending in ".arff" or ".arff.gz" (case-insensitive).
    `boolean` | `isIncremental()` returns whether the loader is an incremental one.
    `static void` | `main(java.lang.String[] args)` for testing only - takes a data file as input.
    `Instance` | `nextElement(Instances dataset)` returns the next element and sets the specified dataset, null if none available.
    `static Instances` | `read(java.io.InputStream stream)` convencience method for loading a dataset in batch mode from a stream.
    `static Instances` | `read(Loader loader)` convencience method for loading a dataset in batch mode.
    `static Instances` | `read(java.lang.String location)` convencience method for loading a dataset in batch mode.
    `void` | `reset()` resets the loader.

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### DataSource

          public DataSource(java.lang.String location)
                     throws java.lang.Exception

      Tries to load the data from the file. Can be either a regular file or a web location (http://, https://, ftp:// or file://).
      Parameters:
        `location` - the name of the file to load
      Throws:
        `java.lang.Exception` - if initialization fails

    - #### DataSource

          public DataSource(Instances inst)

      Initializes the datasource with the given dataset.
      Parameters:
        `inst` - the dataset to use

    - #### DataSource

          public DataSource(Loader loader)

      Initializes the datasource with the given Loader.
      Parameters:
        `loader` - the Loader to use

    - #### DataSource

          public DataSource(java.io.InputStream stream)

      Initializes the datasource with the given input stream. This stream is always interpreted as ARFF.
      Parameters:
        `stream` - the stream to use

  - ### Method Detail

    - #### isArff

          public static boolean isArff(java.lang.String location)

      returns whether the extension of the location is likely to be of ARFF format, i.e., ending in ".arff" or ".arff.gz" (case-insensitive).
      Parameters:
        `location` - the file location to check
      Returns:
        true if the location seems to be of ARFF format

    - #### isIncremental

          public boolean isIncremental()

      returns whether the loader is an incremental one.
      Returns:
        true if the loader is a true incremental one

    - #### getLoader

          public Loader getLoader()

      returns the determined loader, null if the DataSource was initialized with data alone and not a file/URL.
      Returns:
        the loader used for retrieving the data

    - #### getDataSet

          public Instances getDataSet()
                               throws java.lang.Exception

      returns the full dataset, can be null in case of an error.
      Returns:
        the full dataset
      Throws:
        `java.lang.Exception` - if resetting of loader fails

    - #### getDataSet

          public Instances getDataSet(int classIndex)
                               throws java.lang.Exception

      returns the full dataset with the specified class index set, can be null in case of an error.
      Parameters:
        `classIndex` - the class index for the dataset
      Returns:
        the full dataset
      Throws:
        `java.lang.Exception` - if resetting of loader fails

    - #### reset

          public void reset()
                     throws java.lang.Exception

      resets the loader.
      Throws:
        `java.lang.Exception` - if resetting fails

    - #### getStructure

          public Instances getStructure()
                                 throws java.lang.Exception

      returns the structure of the data.
      Returns:
        the structure of the data
      Throws:
        `java.lang.Exception` - if something goes wrong

    - #### getStructure

          public Instances getStructure(int classIndex)
                                 throws java.lang.Exception

      returns the structure of the data, with the defined class index.
      Parameters:
        `classIndex` - the class index for the dataset
      Returns:
        the structure of the data
      Throws:
        `java.lang.Exception` - if something goes wrong

    - #### hasMoreElements

          public boolean hasMoreElements(Instances structure)

      returns whether there are more Instance objects in the data.
      Parameters:
        `structure` - the structure of the dataset
      Returns:
        true if there are more Instance objects available
      See Also:
        `nextElement(Instances)`

    - #### nextElement

          public Instance nextElement(Instances dataset)

      returns the next element and sets the specified dataset, null if none available.
      Parameters:
        `dataset` - the dataset to set for the instance
      Returns:
        the next Instance

    - #### read

          public static Instances read(java.lang.String location)
                                throws java.lang.Exception

      convencience method for loading a dataset in batch mode.
      Parameters:
        `location` - the dataset to load
      Returns:
        the dataset
      Throws:
        `java.lang.Exception` - if loading fails

    - #### read

          public static Instances read(java.io.InputStream stream)
                                throws java.lang.Exception

      convencience method for loading a dataset in batch mode from a stream.
      Parameters:
        `stream` - the stream to load the dataset from
      Returns:
        the dataset
      Throws:
        `java.lang.Exception` - if loading fails

    - #### read

          public static Instances read(Loader loader)
                                throws java.lang.Exception

      convencience method for loading a dataset in batch mode.
      Parameters:
        `loader` - the loader to get the dataset from
      Returns:
        the dataset
      Throws:
        `java.lang.Exception` - if loading fails

    - #### main

          public static void main(java.lang.String[] args)
                           throws java.lang.Exception

      for testing only - takes a data file as input.
      Parameters:
        `args` - the commandline arguments
      Throws:
        `java.lang.Exception` - if something goes wrong

    - #### getRevision

          public java.lang.String getRevision()

      Returns the revision string.
      Specified by:
        `getRevision` in interface `RevisionHandler`
      Returns:
        the revision