TreeNodeVisitor (Java Statistical Analysis Tool 0.0.8 API)

java.lang.Object
- jsat.classifiers.trees.TreeNodeVisitor

All Implemented Interfaces:

Serializable, Cloneable

Direct Known Subclasses:

DecisionTree.Node
```
public abstract class TreeNodeVisitor
extends Object
implements Serializable, Cloneable
```
Provides an abstracted mechanism for traversing and predicting from nodes in a tree meant for a supervised learning problem. Paths and children are used interchangeably, every node has one path to one child
Paths to children nodes can be disabled, but not removed. This is done so that the implementation does not have to worry about changes in the indices to children nodes, which would be complicated to implement. Once a path is disabled, it can not be re-enabled.
If all paths to any children have been disabled, childrenCount() may choose to return 0, otherwise - it must return the original number of paths to children nodes. The implementation for a given tree should override localClassify(jsat.classifiers.DataPoint) and localRegress(jsat.classifiers.DataPoint) if the operations are supported.

Author:

Edward Raff

See Also:

TreeLearner, TreePruner, Serialized Form

Constructor Summary

Constructors
Constructor and Description

TreeNodeVisitor()

Constructors
Constructor and Description
`TreeNodeVisitor()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`abstract int`	`childrenCount()` Returns the number of children this node of the tree has, and may return a non zero value even if the node is a leaf
`CategoricalResults`	`classify(DataPoint dp)`
`abstract TreeNodeVisitor`	`clone()`
`abstract void`	`disablePath(int child)` Disables the selected path to the specified child from the current node.
`abstract Collection<Integer>`	`featuresUsed()` Returns a collection of the indices of the features used by this node in the tree to make its decision about what branch to use next.
`abstract TreeNodeVisitor`	`getChild(int child)` Returns the node for the specific child, or null if the child index was not valid
`abstract int`	`getPath(DataPoint dp)` Returns the path down the tree the given data point would have taken, or -1 if this node was a leaf node OR if a missing value prevent traversal down the path
`double`	`getPathWeight(int path)` Returns the relative weight of each path, which should be an indication of how much of the training data went down each path.
`abstract boolean`	`isLeaf()` Returns true if the node is a leaf, meaning it has no valid paths to any children
`abstract boolean`	`isPathDisabled(int child)` Returns true if the path to the specified child is disabled, meaning it can not be traveled to.
`CategoricalResults`	`localClassify(DataPoint dp)` Returns the classification result that would have been obtained if the current node was a leaf node.
`double`	`localRegress(DataPoint dp)` Returns the regression result that would have been obtained if the current node was a leaf node.
`double`	`regress(DataPoint dp)` Performs regression on the given data point by following it down the tree until it finds the correct terminal node.
`void`	`setPath(int child, TreeNodeVisitor node)` Optional operation! This method, if supported, will set the path so that the child is set to the given value.

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

- Constructor Detail
  - TreeNodeVisitor
```
public TreeNodeVisitor()
```
- Method Detail
  - childrenCount
```
public abstract int childrenCount()
```
    Returns the number of children this node of the tree has, and may return a non zero value even if the node is a leaf
    
    Returns:
    
    the number of children this node has
  - isLeaf
```
public abstract boolean isLeaf()
```
    Returns true if the node is a leaf, meaning it has no valid paths to any children
    
    Returns:
    
    true if the node is purely a leaf node
  - getChild
```
public abstract TreeNodeVisitor getChild(int child)
```
    Returns the node for the specific child, or null if the child index was not valid
    
    Parameters:
    
    child - the index of the child node to obtain
    
    Returns:
    
    the node for the child
  - disablePath
```
public abstract void disablePath(int child)
```
    Disables the selected path to the specified child from the current node. All child indices will not be effected by this operation.
    
    Parameters:
    
    child - the index of the child to disable the path too
  - setPath
```
public void setPath(int child,
                    TreeNodeVisitor node)
```
    Optional operation!
    This method, if supported, will set the path so that the child is set to the given value.
    The implementation may choose to throw an exception if the NodeVisitor is not of the same implementing class.
    
    Parameters:
    
    child - the child path
    
    node - the node to make the child
  - isPathDisabled
```
public abstract boolean isPathDisabled(int child)
```
    Returns true if the path to the specified child is disabled, meaning it can not be traveled to. It will also return true for an invalid child path, since a non existent node can not be reached.
    
    Parameters:
    
    child - the child index to check the path for
    
    Returns:
    
    true if the path is unavailable, false if the path is good.
  - localClassify
```
public CategoricalResults localClassify(DataPoint dp)
```
    Returns the classification result that would have been obtained if the current node was a leaf node.
    
    Parameters:
    
    dp - the data point to localClassify
    
    Returns:
    
    the classification result
    
    Throws:
    
    UnsupportedOperationException - if the tree node does not support or was not trained for classification
  - getPath
```
public abstract int getPath(DataPoint dp)
```
    Returns the path down the tree the given data point would have taken, or -1 if this node was a leaf node OR if a missing value prevent traversal down the path
    
    Parameters:
    
    dp - the data point to send down the tree
    
    Returns:
    
    the path that would be taken
  - getPathWeight
```
public double getPathWeight(int path)
```
    Returns the relative weight of each path, which should be an indication of how much of the training data went down each path. By default, returns 1.0/childrenCount(). The result should sum to one
    
    Parameters:
    
    path - the path to select
    
    Returns:
    
    the fraction of data estimated to travel the specified path, with respect to data that reaches this node.
  - classify
```
public CategoricalResults classify(DataPoint dp)
```
  - localRegress
```
public double localRegress(DataPoint dp)
```
    Returns the regression result that would have been obtained if the current node was a leaf node.
    
    Parameters:
    
    dp - the data point to regress
    
    Returns:
    
    the classification result
    
    Throws:
    
    UnsupportedOperationException - if the tree node does not support or was not trained for classification
  - regress
```
public double regress(DataPoint dp)
```
    Performs regression on the given data point by following it down the tree until it finds the correct terminal node.
    
    Parameters:
    
    dp - the data point to regress
    
    Returns:
    
    the regression result from the tree starting from the current node
  - featuresUsed
```
public abstract Collection<Integer> featuresUsed()
```
    Returns a collection of the indices of the features used by this node in the tree to make its decision about what branch to use next. Numeric features start from zero, and categorical features start from the number of numeric features.
    
    Returns:
    
    the integers indicating which features were used for this node in the tree.
  - clone
```
public abstract TreeNodeVisitor clone()
```
    Overrides:
    
    clone in class Object

Class TreeNodeVisitor

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

TreeNodeVisitor

Method Detail

childrenCount

isLeaf

getChild

disablePath

setPath

isPathDisabled

localClassify

getPath

getPathWeight

classify

localRegress

regress

featuresUsed

clone