BaseDriftDetector (Java Statistical Analysis Tool 0.0.8 API)

java.lang.Object
- jsat.driftdetectors.BaseDriftDetector<V>

All Implemented Interfaces:

Serializable, Cloneable

Direct Known Subclasses:

ADWIN, DDM
```
public abstract class BaseDriftDetector<V>
extends Object
implements Cloneable, Serializable
```
Base class for providing common functionality to drift detection algorithms

Author:

Edward Raff

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected boolean`	`drifting` Set to `true` to indicate that concept drift has occurred
`protected int`	`driftStart` Set this value to the time point where the drift is believed to have started from.
`protected Deque<V>`	`history` Holds the associated object history.
`protected int`	`maxHistory` Controls the maximum amount of history to keep
`protected int`	`time` Tracks the number of updates / trial scene.
`protected boolean`	`warning` Set to `true` to indicate that a warning mode in in effect.

Constructor Summary

Constructors
Modifier Constructor and Description

protected BaseDriftDetector()

protected BaseDriftDetector(BaseDriftDetector<V> toCopy)
Copy constructor

Constructors
Modifier	Constructor and Description
`protected`	`BaseDriftDetector()`
`protected`	`BaseDriftDetector(BaseDriftDetector<V> toCopy)` Copy constructor

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`abstract boolean`	`addSample(double value, V obj)` Adds a new point to the drift detector.
`protected void`	`addToHistory(V obj)` Adds the given item to the history, creating a new history holder if needed.
`void`	`clearHistory()` Clears the current history
`abstract Object`	`clone()`
`void`	`driftHandled()` This method should be called once the drift is handled.
`int`	`getDriftAge()` Returns the number of items in recent history that differed from the historical values, or `-1` if there has not been any detected drift.
`List<V>`	`getDriftedHistory()` Returns a new list containing up to `getMaxHistory()` objects in the history that drifted away from the prior state of the model.
`int`	`getMaxHistory()` Returns the maximum number of items that will be kept in the history.
`boolean`	`isDrifting()` Returns `true` if the algorithm believes that drift has definitely occurred.
`boolean`	`isWarning()` Returns `true` if the algorithm is in a warning state.
`void`	`setMaxHistory(int maxHistory)` Sets the maximum number of items to store in history.

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - time
```
protected int time
```
    Tracks the number of updates / trial scene. May be reset as needed, so long as it increases compared to driftStart
  - maxHistory
```
protected int maxHistory
```
    Controls the maximum amount of history to keep
  - warning
```
protected boolean warning
```
    Set to true to indicate that a warning mode in in effect.
  - drifting
```
protected boolean drifting
```
    Set to true to indicate that concept drift has occurred
  - driftStart
```
protected int driftStart
```
    Set this value to the time point where the drift is believed to have started from. Set to -1 to indicate no drift
  - history
```
protected Deque<V> history
```
    Holds the associated object history. The history is always FIFO, with the end (tail) of the queue containing the most recent object, and the front (head) containing the oldest object.
- Constructor Detail
  - BaseDriftDetector
```
protected BaseDriftDetector()
```
  - BaseDriftDetector
```
protected BaseDriftDetector(BaseDriftDetector<V> toCopy)
```
    Copy constructor
    
    Parameters:
    
    toCopy - the object to copy
- Method Detail
  - isWarning
```
public boolean isWarning()
```
    Returns true if the algorithm is in a warning state. This state indicates that the algorithm believes concept drift may be occurring, but is not confident enough to say that is had definitely occurred.
    Not all algorithms will raise a warning state, and some may only begin keeping track of history once in the warning state.
    
    Returns:
    
    true if concept drift may have started, but is not sure
  - isDrifting
```
public boolean isDrifting()
```
    Returns true if the algorithm believes that drift has definitely occurred. At this
    
    Returns:
  - getMaxHistory
```
public int getMaxHistory()
```
    Returns the maximum number of items that will be kept in the history.
    
    Returns:
    
    the maximum number of items that will be kept in the history.
  - setMaxHistory
```
public void setMaxHistory(int maxHistory)
```
    Sets the maximum number of items to store in history. Setting this to 0 will keep the detector from ever storing history.
    The user can still keep their own independent history or checkpoints by using the isDrifting() and isWarning() methods.
    
    The history size may be changed at any time, but may result in the loss of history.
    
    Parameters:
    
    maxHistory - the new maximum history size of objects added
  - addToHistory
```
protected void addToHistory(V obj)
```
    Adds the given item to the history, creating a new history holder if needed. This method handles the cases where the max history is zero, and when the history is full (dropping the oldest)
    
    Parameters:
    
    obj - the object to add to the history
  - clearHistory
```
public void clearHistory()
```
    Clears the current history
  - getDriftAge
```
public int getDriftAge()
```
    Returns the number of items in recent history that differed from the historical values, or -1 if there has not been any detected drift. This method will return -1 even if isWarning() is true.
    
    Returns:
    
    the number of updates ago that the drift started, or -1 if no drift has occurred
  - getDriftedHistory
```
public List<V> getDriftedHistory()
```
    Returns a new list containing up to getMaxHistory() objects in the history that drifted away from the prior state of the model.
    The 0 index in the list will be the most recently added item, and the largest index will be the oldest item.
    
    Returns:
    
    the list of objects that make up the effected history
  - addSample
```
public abstract boolean addSample(double value,
                                  V obj)
```
    Adds a new point to the drift detector. If an escalation in state occurs, true will be returned. A change of state could be either drift occurring isDrifting() or a warning state isWarning(). If the detector was in a warning state and then goes back to normal, false will be returned.
    
    For binary (true / false) drift detectors, value will be considered false if and only if its value is equal to zero. Any non zero value will be treated as true
    
    Objects added with the value may or may not be added to the history, the behavior is algorithm dependent. Some may always add it to the history, while others will only begin collecting history once a warning state occurs.
    
    Parameters:
    
    value - the numeric value to add to the drift detector
    
    obj - the object associated with this value. It may or may not be stored in the detectors history
    
    Returns:
    
    true if a drift has or may be starting.
    
    Throws:
    
    UnhandledDriftException - if driftHandled() is not called after drifting is detected
  - driftHandled
```
public void driftHandled()
```
    This method should be called once the drift is handled. Once done, this method will clear the flags and prepare the detector to continue tracking drift again.
    By using this method, one can continue to track multiple future drift changes without having to feed the history data (which may be incomplete) into a new detector object.
  - clone
```
public abstract Object clone()
```
    Overrides:
    
    clone in class Object

Class BaseDriftDetector<V>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

time

maxHistory

warning

drifting

driftStart

history

Constructor Detail

BaseDriftDetector

BaseDriftDetector

Method Detail

isWarning

isDrifting

getMaxHistory

setMaxHistory

addToHistory

clearHistory

getDriftAge

getDriftedHistory

addSample

driftHandled

clone