Package weka.core.converters

Interface Loader

All Superinterfaces:
RevisionHandler, Serializable
All Known Implementing Classes:
AbstractFileLoader, AbstractLoader, ArffLoader, C45Loader, CSVLoader, DatabaseLoader, JSONLoader, LibSVMLoader, MatlabLoader, SerializedInstancesLoader, SVMLightLoader, TextDirectoryLoader, XRFFLoader
public interface Loader extends Serializable, RevisionHandler
Interface to something that can load Instances from an input source in some format.
Version:
$Revision: 9866 $
Author:
Mark Hall (mhall@cs.waikato.ac.nz)

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static class 
    Loader.StructureNotReadyException
    Exception that implementers can throw from getStructure() when they have not been configured sufficiently in order to read the structure (or data).

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    BATCH
     
    static final int
    INCREMENTAL
     
    static final int
    NONE
    The retrieval modes

  • Method Summary

    Modifier and Type
    Method
    Description
    Instances
    getDataSet()
    Return the full data set.
    Instance
    getNextInstance(Instances structure)
    Read the data set incrementally---get the next instance in the data set or returns null if there are no more instances to get.
    Instances
    getStructure()
    Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.
    void
    reset()
    Resets the Loader object ready to begin loading.
    void
    setRetrieval(int mode)
    Sets the retrieval mode.
    void
    setSource(File file)
    Resets the Loader object and sets the source of the data set to be the supplied File object.
    void
    setSource(InputStream input)
    Resets the Loader object and sets the source of the data set to be the supplied InputStream.

    Methods inherited from interface weka.core.RevisionHandler

    getRevision

  • Field Details

  • Method Details

    • setRetrieval

      void setRetrieval(int mode)
      Sets the retrieval mode. Note: Some loaders may not be able to implement incremental loading.
      Parameters:
      mode - the retrieval mode

    • reset

      void reset() throws Exception
      Resets the Loader object ready to begin loading. If there is an existing source, implementations should attempt to reset in such a fashion as to be able to load from the beginning of the source.
      Throws:
      Exception - if Loader can't be reset for some reason.

    • setSource

      void setSource(File file) throws IOException
      Resets the Loader object and sets the source of the data set to be the supplied File object.
      Parameters:
      file - the File
      Throws:
      IOException - if an error occurs support loading from a File. 
       
    public_normal_behavior
      requires: file != null
                && (* file exists *);
      modifiable: model_sourceSupplied, model_structureDetermined;
      ensures: model_sourceSupplied == true 
               && model_structureDetermined == false;
  also
    public_exceptional_behavior
      requires: file == null
                || (* file does not exist *);
    signals: (IOException);

    • setSource

      void setSource(InputStream input) throws IOException
      Resets the Loader object and sets the source of the data set to be the supplied InputStream.
      Parameters:
      input - the source InputStream
      Throws:
      IOException - if this Loader doesn't support loading from a File.

    • getStructure

      Instances getStructure() throws IOException
      Determines and returns (if possible) the structure (internally the header) of the data set as an empty set of instances.
      Returns:
      the structure of the data set as an empty set of Instances
      Throws:
      IOException - if there is no source or parsing fails 
       
    public_normal_behavior
      requires: model_sourceSupplied == true
                && model_structureDetermined == false
                && (* successful parse *);
      modifiable: model_structureDetermined;
      ensures: \result != null
               && \result.numInstances() == 0
               && model_structureDetermined == true;
  also
    public_exceptional_behavior
      requires: model_sourceSupplied == false
                || (* unsuccessful parse *);
      signals: (IOException);

    • getDataSet

      Instances getDataSet() throws IOException
      Return the full data set. If the structure hasn't yet been determined by a call to getStructure then the method should do so before processing the rest of the data set.
      Returns:
      the full data set as an Instances object
      Throws:
      IOException - if there is an error during parsing or if getNextInstance has been called on this source (either incremental or batch loading can be used, not both). 
       
    public_normal_behavior
      requires: model_sourceSupplied == true
                && (* successful parse *);
      modifiable: model_structureDetermined;
      ensures: \result != null
               && \result.numInstances() >= 0
               && model_structureDetermined == true;
  also
    public_exceptional_behavior
      requires: model_sourceSupplied == false
                || (* unsuccessful parse *);
      signals: (IOException);

    • getNextInstance

      Instance getNextInstance(Instances structure) throws IOException
      Read the data set incrementally---get the next instance in the data set or returns null if there are no more instances to get. If the structure hasn't yet been determined by a call to getStructure then method should do so before returning the next instance in the data set. If it is not possible to read the data set incrementally (ie. in cases where the data set structure cannot be fully established before all instances have been seen) then an exception should be thrown.
      Parameters:
      structure - the dataset header information, will get updated in case of string or relational attributes
      Returns:
      the next instance in the data set as an Instance object or null if there are no more instances to be read
      Throws:
      IOException - if there is an error during parsing or if getDataSet has been called on this source (either incremental or batch loading can be used, not both).