edu.stanford.nlp.trees
Class Tree

java.lang.Object
  extended by java.util.AbstractCollection<Tree>
      extended by edu.stanford.nlp.trees.Tree
All Implemented Interfaces:
Label, Labeled, Scored, Serializable, Iterable<Tree>, Collection<Tree>
Direct Known Subclasses:
LabeledScoredTreeLeaf, LabeledScoredTreeNode, SimpleTree, TreeGraphNode

public abstract class Tree
extends AbstractCollection<Tree>
implements Label, Labeled, Scored, Serializable, Iterable<Tree>

The abstract class Tree is used to collect all of the tree types, and acts as a generic extendable type. This is the standard implementation of inheritance-based polymorphism. All Tree objects support accessors for their children (a Tree[]), their label (a Label), and their score (a double). However, different concrete implementations may or may not include the latter two, in which case a default value is returned. The class Tree defines no data fields. The two abstract methods that must be implemented are: children(), and treeFactory(). Notes that setChildren(Tree[]) is now an optional operation, whereas it was previously required to be implemented. There is now support for finding the parent of a tree. This may be done by search from a tree root, or via a directly stored parent. The Tree class now implements the Collection interface: in terms of this, each node of the tree is an element of the collection; hence one can explore the tree by using the methods of this interface. A Tree is regarded as a read-only Collection (even though the Tree class has various methods that modify trees). Moreover, the implementation is not thread-safe: no attempt is made to detect and report concurrent modifications.

Author:
Christopher Manning, Dan Klein, Sarah Spikes (sdspikes@cs.stanford.edu) - filled in types
See Also:
Serialized Form

Field Summary
static boolean DISPLAY_SCORES
           
static Tree[] EMPTY_TREE_ARRAY
          A leaf node should have a zero-length array for its children.
 
Constructor Summary
Tree()
           
 
Method Summary
 void addChild(int i, Tree t)
          Adds the tree t at the index position among the daughters.
 void addChild(Tree t)
          Adds the tree t at the last index position among the daughters.
 Tree ancestor(int height, Tree root)
          Return the ancestor tree node height nodes up from the current node.
 boolean cCommands(Tree t1, Tree t2)
          Given nodes t1 and t2 which are dominated by this node, returns true iff t1 c-commands t2.
abstract  Tree[] children()
          Returns an array of children for the current node.
 Set<Constituent> constituents()
          Returns the Constituents generated by the parse tree.
 Set<Constituent> constituents(ConstituentFactory cf)
          Returns the Constituents generated by the parse tree.
 Set<Constituent> constituents(ConstituentFactory cf, boolean charLevel)
          Returns the Constituents generated by the parse tree.
 Tree deepCopy()
          Create a deep copy of the tree.
 Tree deepCopy(TreeFactory tf)
          Create a deep copy of the tree.
 Tree deeperCopy()
          Same as deepCopy but makes a copy of the labels as well.
 Tree deeperCopy(TreeFactory tf)
          Same as deepCopy but makes a copy of the labels as well.
 Tree deeperCopy(TreeFactory tf, LabelFactory lf)
          Same as deepCopy but will copy the labels over as well.
 Set<Dependency<Label,Label,Object>> dependencies()
          Return a set of Word-Word dependencies, represented as Dependency objects, for the Tree.
 Set<Dependency<Label,Label,Object>> dependencies(Filter<Dependency<Label,Label,Object>> f)
          Return a set of Word-Word dependencies, represented as Dependency objects, for the Tree.
 Set<Dependency<Label,Label,Object>> dependencies(Filter<Dependency<Label,Label,Object>> f, HeadFinder hf)
          Return a set of Word-Word dependencies, represented as Dependency objects, for the Tree.
 Set<Dependency<Label,Label,Object>> dependencies(HeadFinder hf)
          Return a set of Word-Word dependencies, represented as Dependency objects for the Tree.
 int depth()
          Finds the depth of the tree.
 int depth(Tree node)
          Finds the distance from this node to the specified node.
 boolean dominates(Tree t)
          Returns true if this dominates the Tree passed in as an argument.
 List<Tree> dominationPath(Tree t)
          Returns the path of nodes leading down to a dominated node, including this and the dominated node itself.
 boolean equals(Object o)
          Implements equality for Tree's.
 Tree firstChild()
          Returns the first child of a tree, or null if none.
 Tree flatten()
          Return a flattened version of a tree.
 Tree flatten(TreeFactory tf)
          Return a flattened version of a tree.
 Tree getChild(int i)
          Return the child at some daughter index.
 List<Tree> getChildrenAsList()
          Returns a List of children for the current node.
 List<Tree> getLeaves()
          Gets the leaves of the tree.
 List<Tree> getLeaves(List<Tree> list)
          Gets the leaves of the tree.
 Tree getNodeNumber(int i)
          Fetches the ith node in the tree, with node numbers defined as in nodeNumber(Tree).
 IntPair getSpan()
           
 int hashCode()
          Implements a hashCode for Tree's.
 Tree headPreTerminal(HeadFinder hf)
          Returns the preterminal tree that is the head of the tree.
 Tree headTerminal(HeadFinder hf)
          Returns the tree leaf that is the head of the tree.
 Tree headTerminal(HeadFinder hf, Tree parent)
          Returns the tree leaf that is the head of the tree.
 void indentedListPrint()
          Indented list printing of a tree.
 void indentedListPrint(PrintWriter pw, boolean printScores)
          Indented list printing of a tree.
 void indexLeaves()
          Assign sequential integer indices to the leaves of the tree rooted at this Tree, starting with 1.
 int indexOf(Tree tree)
          Returns the position of a Tree in the children list, if present, or -1 if it is not present.
 void indexSpans(int startIndex)
           
 Pair<Integer,Integer> indexSpans(MutableInteger startIndex)
          Assigns span indices (BeginIndexAnnotation and EndIndexAnnotation) to all nodes in a tree.
 void insertDtr(Tree dtr, int position)
          insert dtr after position existing daughters in this.
 boolean isLeaf()
          Says whether a node is a leaf.
 boolean isPhrasal()
          Return whether this node is a phrasal node or not.
 boolean isPrePreTerminal()
          Return whether all the children of this node are preterminals or not.
 boolean isPreTerminal()
          Return whether this node is a preterminal or not.
 boolean isUnaryRewrite()
          Says whether the current node has only one child.
 Iterator<Tree> iterator()
          Returns an iterator over all the nodes of the tree.
 Tree joinNode(Tree t1, Tree t2)
          Given nodes t1 and t2 which are dominated by this node, returns their "join node": the node j such that j dominates both t1 and t2, and every other node which dominates both t1 and t2 dominates j.
 Label label()
          Returns the label associated with the current node, or null if there is no label.
 List<LabeledWord> labeledYield()
           
 List<LabeledWord> labeledYield(List<LabeledWord> ty)
           
 LabelFactory labelFactory()
          Returns a factory that makes labels of the same type as this one.
 Collection<Label> labels()
          Get the set of all node and leaf Labels, null or otherwise, contained in the tree.
 Tree lastChild()
          Returns the last child of a tree, or null if none.
 int leftCharEdge(Tree node)
          Returns the positional index of the left edge of node within the tree, as measured by characters.
 Tree localTree()
          Returns a new Tree that represents the local Tree at a certain node.
 Set<Tree> localTrees()
          Returns a set of one level Trees that ares the local trees of the tree.
 Set<Dependency<Label,Label,Object>> mapDependencies(Filter<Dependency<Label,Label,Object>> f, HeadFinder hf)
          Return a set of Label-Label dependencies, represented as Dependency objects, for the Tree.
 Set<Dependency<Label,Label,Object>> mapDependencies(Filter<Dependency<Label,Label,Object>> f, HeadFinder hf, String rootName)
          Return a set of Label-Label dependencies, represented as Dependency objects, for the Tree.
 int nodeNumber(Tree root)
          Calculates the node's number, defined as the number of nodes traversed in a left-to-right, depth-first search of the tree starting at root and ending at this.
 String nodeString()
          Returns the label of a tree node as a String.
 int numChildren()
          Says how many children a tree node has in its local tree.
 Tree parent()
          Return the parent of the tree node.
 Tree parent(Tree root)
          Return the parent of the tree node.
 List<Tree> pathNodeToNode(Tree t1, Tree t2)
          Given nodes t1 and t2 which are dominated by this node, returns a list of all the nodes on the path from t1 to t2, inclusive, or null if none found.
 void pennPrint()
          Print the tree as done in Penn Treebank merged files.
 void pennPrint(PrintStream ps)
          Print the tree as done in Penn Treebank merged files.
 void pennPrint(PrintWriter pw)
          Print the tree as done in Penn Treebank merged files.
 String pennString()
          Calls pennPrint() and saves output to a String
 void percolateHeads(HeadFinder hf)
          Finds the heads of the tree.
 List<Tree> postOrderNodeList()
           
 List<Tree> preOrderNodeList()
           
 List<Label> preTerminalYield()
          Gets the preterminal yield (i.e., tags) of the tree.
 List<Label> preTerminalYield(List<Label> y)
          Gets the preterminal yield (i.e., tags) of the tree.
 void printLocalTree()
           
 void printLocalTree(PrintWriter pw)
           
 Tree prune(Filter<Tree> filter)
          Creates a deep copy of the tree, where all nodes that the filter does not accept and all children of such nodes are pruned.
 Tree prune(Filter<Tree> filter, TreeFactory tf)
          Creates a deep copy of the tree, where all nodes that the filter does not accept and all children of such nodes are pruned.
 Tree removeChild(int i)
          Destructively removes the child at some daughter index and returns it.
 int rightCharEdge(Tree node)
          Returns the positional index of the right edge of node within the tree, as measured by characters.
 double score()
          Returns the score associated with the current node, or NaN if there is no score.
 Tree setChild(int i, Tree t)
          Replaces the ith child of this with the tree t.
 void setChildren(List<Tree> childTreesList)
          Set the children of this tree node to the given list.
 void setChildren(Tree[] children)
          Set the children of this node to be the children given in the array.
 void setFromString(String labelStr)
          Set the contents of this label to this String representing the complete contents of the label.
 void setLabel(Label label)
          Sets the label associated with the current node, if there is one.
 void setLabels(Collection<Label> c)
          Sets the labels associated with this object.
 void setScore(double score)
          Sets the score associated with the current node, if there is one.
 void setSpans()
           
 void setValue(String value)
          Set the value for the label (if one is stored).
 List<Tree> siblings(Tree root)
          Returns the siblings of this Tree node.
 int size()
          Returns the number of nodes the tree contains.
 Tree skipRoot()
          Returns first child if it is single and if the label at the current node is either "ROOT" or empty.
 Tree spliceOut(Filter<Tree> nodeFilter)
          Creates a (partial) deep copy of the tree, where all nodes that the filter does not accept are spliced out.
 Tree spliceOut(Filter<Tree> nodeFilter, TreeFactory tf)
          Creates a (partial) deep copy of the tree, where all nodes that the filter does not accept are spliced out.
 List<Tree> subTreeList()
          Get the list of all subtrees inside the tree by returning a tree rooted at each node.
 Set<Tree> subTrees()
          Get the set of all subtrees inside the tree by returning a tree rooted at each node.
<T extends Collection<Tree>>
T
subTrees(T n)
          Add the set of all subtrees inside a tree (including the tree itself) to the given Collection.
 Set<Dependency<Label,Label,Object>> taggedDependencies()
          Return a Set of TaggedWord-TaggedWord dependencies, represented as Dependency objects, for the Tree.
 Set<Dependency<Label,Label,Object>> taggedDependencies(Filter<Dependency<Label,Label,Object>> f)
          Return a set of TaggedWord-TaggedWord dependencies, represented as Dependency objects, for the Tree.
 Set<Dependency<Label,Label,Object>> taggedDependencies(Filter<Dependency<Label,Label,Object>> f, HeadFinder hf)
          Return a set of TaggedWord-TaggedWord dependencies, represented as Dependency objects, for the Tree.
 Set<Dependency<Label,Label,Object>> taggedDependencies(HeadFinder hf)
          Return a set of TaggedWord-TaggedWord dependencies, represented as Dependency objects for the Tree.
 Sentence<TaggedWord> taggedYield()
          Gets the tagged yield of the tree.
<X extends List<TaggedWord>>
X
taggedYield(X ty)
          Gets the tagged yield of the tree -- that is, get the preterminals as well as the terminals.
 String toString()
          Converts parse tree to string in Penn Treebank format.
 StringBuilder toStringBuilder(StringBuilder sb)
          Appends the printed form of a parse tree (as a bracketed String) to an Appendable, such as a StringBuffer.
 StringBuilder toStringBuilder(StringBuilder sb, boolean printOnlyLabelValue)
          Appends the printed form of a parse tree (as a bracketed String) to an Appendable, such as a StringBuffer.
 String toStructureDebugString()
          Returns a String reporting what kinds of Tree and Label nodes this Tree contains.
 Tree transform(TreeTransformer transformer)
          Create a transformed Tree.
 Tree transform(TreeTransformer transformer, TreeFactory tf)
          Create a transformed Tree.
abstract  TreeFactory treeFactory()
          Return a TreeFactory that produces trees of the appropriate type.
 Tree upperMostUnary(Tree root)
          Return the highest node of the (perhaps trivial) unary chain that this node is part of.
 String value()
          Return a String representation of just the "main" value of this label.
static Tree valueOf(String str)
          This gives you a tree from a String representation (as a bracketed Tree, of the kind produced by toString(), pennPrint(), or as in the Penn Treebank).
static Tree valueOf(String str, TreeReaderFactory trf)
          This gives you a tree from a String representation (as a bracketed Tree, of the kind produced by toString(), pennPrint(), or as in the Penn Treebank.
<X extends HasWord>
Sentence<X>
yield()
          Gets the yield of the tree.
<T> List<T>
yield(List<T> y)
          Gets the yield of the tree.
<X extends HasWord>
Sentence<X>
yield(Sentence<X> y)
          Gets the yield of the tree.
 
Methods inherited from class java.util.AbstractCollection
add, addAll, clear, contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

EMPTY_TREE_ARRAY

public static final Tree[] EMPTY_TREE_ARRAY
A leaf node should have a zero-length array for its children. For efficiency, classes can use this array as a return value for children() for leaf nodes if desired. This can also be used elsewhere when you want an empty Tree array.


DISPLAY_SCORES

public static boolean DISPLAY_SCORES
Constructor Detail

Tree

public Tree()
Method Detail

isLeaf

public boolean isLeaf()
Says whether a node is a leaf. Can be used on an arbitrary Tree. Being a leaf is defined as having no children. This must be implemented as returning a zero-length Tree[] array for children(). This is the preferred alternative to running meta checks on types, as it works independent of Tree implementation.

Returns:
true if this object is a leaf

numChildren

public int numChildren()
Says how many children a tree node has in its local tree. Can be used on an arbitrary Tree. Being a leaf is defined as having no children.

Returns:
The number of direct children of the tree node

isUnaryRewrite

public boolean isUnaryRewrite()
Says whether the current node has only one child. Can be used on an arbitrary Tree.

Returns:
Whether the node heads a unary rewrite

isPreTerminal

public boolean isPreTerminal()
Return whether this node is a preterminal or not. A preterminal is defined to be a node with one child which is itself a leaf.

Returns:
true if the node is a preterminal; false otherwise

isPrePreTerminal

public boolean isPrePreTerminal()
Return whether all the children of this node are preterminals or not. A preterminal is defined to be a node with one child which is itself a leaf. Considered false if the node has no children

Returns:
true if the node is a prepreterminal; false otherwise

isPhrasal

public boolean isPhrasal()
Return whether this node is a phrasal node or not. A phrasal node is defined to be a node which is not a leaf or a preterminal. Worded positively, this means that it must have two or more children, or one child that is not a leaf.

Returns:
true if the node is phrasal; false otherwise

equals

public boolean equals(Object o)
Implements equality for Tree's. Two Tree objects are equal if they have equal Labels, the same number of children, and their children are pairwise equal.

Specified by:
equals in interface Collection<Tree>
Overrides:
equals in class Object
Parameters:
o - The object to compare with
Returns:
Whether two things are equal

hashCode

public int hashCode()
Implements a hashCode for Tree's. Two trees should have the same hashcode if they are equal, so we hash on the label, the label and the children's labels.

Specified by:
hashCode in interface Collection<Tree>
Overrides:
hashCode in class Object
Returns:
The hash code

indexOf

public int indexOf(Tree tree)
Returns the position of a Tree in the children list, if present, or -1 if it is not present. Trees are checked for presence with equals().

Parameters:
tree - The tree to look for in children list
Returns:
Its index in the list or -1

children

public abstract Tree[] children()
Returns an array of children for the current node. If there are no children (if the node is a leaf), this must return a Tree[] array of length 0. A null children() value for tree leaves was previously supported, but no longer is. A caller may assume that either isLeaf() returns true, or this node has a nonzero number of children.

Returns:
The children of the node
See Also:
getChildrenAsList()

getChildrenAsList

public List<Tree> getChildrenAsList()
Returns a List of children for the current node. If there are no children, then a (non-null) List<Tree> of size 0 will be returned. The list has new list structure but pointers to, not copies of the children. That is, the returned list is mutable, and simply adding to or deleting items from it is safe, but beware changing the contents of the children.

Returns:
The children of the node

setChildren

public void setChildren(Tree[] children)
Set the children of this node to be the children given in the array. This is an optional operation; by default it is unsupported. Note for subclasses that if there are no children, the children() method must return a Tree[] array of length 0. This class gives subclasses access to a protected ZEROCHILDREN canonical zero-length Tree[] array to represent zero children, but it is not required that leaf nodes use this particular zero-length array to represent a leaf node.

Parameters:
children - The array of children, each a Tree
See Also:
setChildren(List)

setChildren

public void setChildren(List<Tree> childTreesList)
Set the children of this tree node to the given list. This method is implemented in the Tree class by converting the List into a tree array and calling the array-based method. Subclasses which use a List-based representation of tree children should override this method. This implementation allows the case that the List is null: it yields a node with no children (represented by a canonical zero-length children() array).

Parameters:
childTreesList - A list of trees to become children of the node. This method does not retain the List that you pass it (copying is done), but it will retain the individual children (they are not copied).
See Also:
setChildren(Tree[])

label

public Label label()
Returns the label associated with the current node, or null if there is no label. The default implementation always returns null.

Specified by:
label in interface Labeled
Returns:
The label of the node

setLabel

public void setLabel(Label label)
Sets the label associated with the current node, if there is one.

Specified by:
setLabel in interface Labeled
Parameters:
label - The label

score

public double score()
Returns the score associated with the current node, or NaN if there is no score. The default implementation returns NaN.

Specified by:
score in interface Scored
Returns:
The score

setScore

public void setScore(double score)
Sets the score associated with the current node, if there is one.

Parameters:
score - The score

firstChild

public Tree firstChild()
Returns the first child of a tree, or null if none.

Returns:
The first child

lastChild

public Tree lastChild()
Returns the last child of a tree, or null if none.

Returns:
The last child

upperMostUnary

public Tree upperMostUnary(Tree root)
Return the highest node of the (perhaps trivial) unary chain that this node is part of. In case this node is the only child of its parent, trace up the chain of unaries, and return the uppermost node of the chain (the node whose parent has multiple children, or the node that is the root of the tree).

Parameters:
root - The root of the tree that contains this subtree
Returns:
The uppermost node of the unary chain, if this node is in a unary chain, or else the current node

setSpans

public void setSpans()

getSpan

public IntPair getSpan()

constituents

public Set<Constituent> constituents()
Returns the Constituents generated by the parse tree. Constituents are computed with respect to whitespace (e.g., at the word level).

Returns:
a Set of the constituents as constituents of type Constituent

constituents

public Set<Constituent> constituents(ConstituentFactory cf)
Returns the Constituents generated by the parse tree. The Constituents of a sentence include the preterminal categories but not the leaves.

Parameters:
cf - ConstituentFactory used to build the Constituent objects
Returns:
a Set of the constituents as SimpleConstituent type (in the current implementation, a HashSet

constituents

public Set<Constituent> constituents(ConstituentFactory cf,
                                     boolean charLevel)
Returns the Constituents generated by the parse tree. The Constituents of a sentence include the preterminal categories but not the leaves.

Parameters:
cf - ConstituentFactory used to build the Constituent objects
charLevel - If true, compute bracketings irrespective of whitespace boundaries.
Returns:
a Set of the constituents as SimpleConstituent type (in the current implementation, a HashSet

localTree

public Tree localTree()
Returns a new Tree that represents the local Tree at a certain node. That is, it builds a new tree that copies the mother and daughter nodes (but not their Labels), as non-Leaf nodes, but zeroes out their children.

Returns:
A local tree

localTrees

public Set<Tree> localTrees()
Returns a set of one level Trees that ares the local trees of the tree. That is, it builds a new tree that copies the mother and daughter nodes (but not their Labels), for each phrasal node, but zeroes out their children.

Returns:
A set of local tree

toStructureDebugString

public String toStructureDebugString()
Returns a String reporting what kinds of Tree and Label nodes this Tree contains.


toStringBuilder

public StringBuilder toStringBuilder(StringBuilder sb)
Appends the printed form of a parse tree (as a bracketed String) to an Appendable, such as a StringBuffer. The implementation of this may be more efficient than for toString() on complex trees.

Parameters:
sb - The StringBuilder to which the tree will be appended
Returns:
Returns the StringBuilder passed in with extra stuff in it

toStringBuilder

public StringBuilder toStringBuilder(StringBuilder sb,
                                     boolean printOnlyLabelValue)
Appends the printed form of a parse tree (as a bracketed String) to an Appendable, such as a StringBuffer. The implementation of this may be more efficient than for toString() on complex trees.

Parameters:
sb - The StringBuilder to which the tree will be appended
printOnlyLabelValue - If true, print only the value() of each node's label
Returns:
Returns the StringBuilder passed in with extra stuff in it

toString

public String toString()
Converts parse tree to string in Penn Treebank format. Get efficiency by chaining a single StringBuffer through it all.

Specified by:
toString in interface Label
Overrides:
toString in class AbstractCollection<Tree>
Returns:
the tree as a bracketed list on one line

printLocalTree

public void printLocalTree()

printLocalTree

public void printLocalTree(PrintWriter pw)

indentedListPrint

public void indentedListPrint()
Indented list printing of a tree. The tree is printed in an indented list notation, with nodel labels followed by node scores.


indentedListPrint

public void indentedListPrint(PrintWriter pw,
                              boolean printScores)
Indented list printing of a tree. The tree is printed in an indented list notation, with nodel labels followed by node scores.

Parameters:
pw - The PrintWriter to print the tree to
printScores - Whether to print the scores (log probs) of tree nodes

nodeString

public String nodeString()
Returns the label of a tree node as a String. This is done by calling toString() on the Label, but if the label is null or has a null, value, then this method returns an empty String.

Returns:
The label of a tree node as a String

pennPrint

public void pennPrint(PrintWriter pw)
Print the tree as done in Penn Treebank merged files. The formatting should be exactly the same, but we don't print the trailing whitespace found in Penn Treebank trees. The basic deviation from a bracketed indented tree is to in general collapse the printing of adjacent preterminals onto one line of tasg and words. Additional complexities are that conjunctions (tag CC) are not collapsed in this way, and that the unlabeled outer brackets are collapsed onto the same line as the next bracket down.

Parameters:
pw - The tree is printed to this PrintWriter

pennPrint

public void pennPrint(PrintStream ps)
Print the tree as done in Penn Treebank merged files. The formatting should be exactly the same, but we don't print the trailing whitespace found in Penn Treebank trees. The basic deviation from a bracketed indented tree is to in general collapse the printing of adjacent preterminals onto one line of tags and words. Additional complexities are that conjunctions (tag CC) are not collapsed in this way, and that the unlabeled outer brackets are collapsed onto the same line as the next bracket down.

Parameters:
ps - The tree is printed to this PrintStream

pennString

public String pennString()
Calls pennPrint() and saves output to a String

Returns:
The indent S-expression representation of a Tree

pennPrint

public void pennPrint()
Print the tree as done in Penn Treebank merged files. The formatting should be exactly the same, but we don't print the trailing whitespace found in Penn Treebank trees. The tree is printed to System.out. The basic deviation from a bracketed indented tree is to in general collapse the printing of adjacent preterminals onto one line of tags and words. Additional complexities are that conjunctions (tag CC) are not collapsed in this way, and that the unlabeled outer brackets are collapsed onto the same line as the next bracket down.


depth

public int depth()
Finds the depth of the tree. The depth is defined as the length of the longest path from this node to a leaf node. Leaf nodes have depth zero. POS tags have depth 1. Phrasal nodes have depth >= 2.

Returns:
the depth

depth

public int depth(Tree node)
Finds the distance from this node to the specified node. return -1 if this is not an ancestor of node.

Parameters:
node - A subtree contained in this tree
Returns:
the depth

headTerminal

public Tree headTerminal(HeadFinder hf,
                         Tree parent)
Returns the tree leaf that is the head of the tree.

Parameters:
hf - The head-finding algorithm to use
parent - The parent of this tree
Returns:
The head tree leaf if any, else null

headTerminal

public Tree headTerminal(HeadFinder hf)
Returns the tree leaf that is the head of the tree.

Parameters:
hf - The headfinding algorithm to use
Returns:
The head tree leaf if any, else null

headPreTerminal

public Tree headPreTerminal(HeadFinder hf)
Returns the preterminal tree that is the head of the tree. See isPreTerminal() for the definition of a preterminal node. Beware that some tree nodes may have no preterminal head.

Parameters:
hf - The headfinding algorithm to use
Returns:
The head preterminal tree, if any, else null
Throws:
IllegalArgumentException - if called on a leaf node

percolateHeads

public void percolateHeads(HeadFinder hf)
Finds the heads of the tree. This code assumes that the label does store and return sensible values for the category, word, and tag. It will be a no-op otherwise. The tree is modified. The routine assumes the Tree has word leaves and tag preterminals, and copies their category to word and tag respectively, if they have a null value.

Parameters:
hf - The headfinding algorithm to use

dependencies

public Set<Dependency<Label,Label,Object>> dependencies()
Return a set of Word-Word dependencies, represented as Dependency objects, for the Tree. This will only give useful results if the internal tree node labels support HasWord and head percolation has already been done (see percolateHeads()).

Returns:
Set of dependencies (each a Dependency)

dependencies

public Set<Dependency<Label,Label,Object>> dependencies(Filter<Dependency<Label,Label,Object>> f)
Return a set of Word-Word dependencies, represented as Dependency objects, for the Tree. This will only give useful results if the internal tree node labels support HasWord and head percolation has already been done (see percolateHeads()).

Parameters:
f - Dependencies are excluded for which the Dependency is not accepted by the Filter
Returns:
Set of dependencies (each a Dependency)

dependencies

public Set<Dependency<Label,Label,Object>> dependencies(HeadFinder hf)
Return a set of Word-Word dependencies, represented as Dependency objects for the Tree.

Parameters:
hf - The HeadFinder to use to identify the head of constituents
Returns:
Set of dependencies (each a Dependency)

dependencies

public Set<Dependency<Label,Label,Object>> dependencies(Filter<Dependency<Label,Label,Object>> f,
                                                        HeadFinder hf)
Return a set of Word-Word dependencies, represented as Dependency objects, for the Tree.

Parameters:
f - Dependencies are excluded for which the Dependency is not accepted by the Filter
hf - The HeadFinder to use to identify the head of constituents. If this is null, then nodes are assumed to already be marked with their heads.
Returns:
Set of dependencies (each a Dependency)

taggedDependencies

public Set<Dependency<Label,Label,Object>> taggedDependencies()
Return a Set of TaggedWord-TaggedWord dependencies, represented as Dependency objects, for the Tree. This will only give useful results if the internal tree node labels support HasWord and HasTag, and head percolation has already been done (see percolateHeads()).

Returns:
Set of dependencies (each a Dependency)

taggedDependencies

public Set<Dependency<Label,Label,Object>> taggedDependencies(Filter<Dependency<Label,Label,Object>> f)
Return a set of TaggedWord-TaggedWord dependencies, represented as Dependency objects, for the Tree. This will only give useful results if the internal tree node labels support HasWord and head percolation has already been done (see percolateHeads()).

Implementation note: It would be nice to generalize this with dependencies() to use a LabelFactory, but it seems impossible with the current setup.

Parameters:
f - Dependencies are excluded for which the Dependency is not accepted by the Filter
Returns:
Set of dependencies (each a Dependency)

taggedDependencies

public Set<Dependency<Label,Label,Object>> taggedDependencies(HeadFinder hf)
Return a set of TaggedWord-TaggedWord dependencies, represented as Dependency objects for the Tree.

Parameters:
hf - The HeadFinder to use to identify the head of constituents
Returns:
Set of dependencies (each a Dependency)

taggedDependencies

public Set<Dependency<Label,Label,Object>> taggedDependencies(Filter<Dependency<Label,Label,Object>> f,
                                                              HeadFinder hf)
Return a set of TaggedWord-TaggedWord dependencies, represented as Dependency objects, for the Tree.

Parameters:
f - Dependencies are excluded for which the Dependency is not accepted by the Filter
hf - The HeadFinder to use to identify the head of constituents. If this is null, then nodes are assumed to already be marked with their heads.
Returns:
Set of dependencies (each a Dependency)

mapDependencies

public Set<Dependency<Label,Label,Object>> mapDependencies(Filter<Dependency<Label,Label,Object>> f,
                                                           HeadFinder hf)
Return a set of Label-Label dependencies, represented as Dependency objects, for the Tree. The Labels are the ones of the leaf nodes of the tree, without mucking with them.

Parameters:
f - Dependencies are excluded for which the Dependency is not accepted by the Filter
hf - The HeadFinder to use to identify the head of constituents. The code assumes that it can use headPreTerminal(hf) to find a tag and word to make a CyclicCoreLabel.
Returns:
Set of dependencies (each a Dependency between two CyclicCoreLabels, which each contain a tag(), word(), and value(), the last two of which are identical).

mapDependencies

public Set<Dependency<Label,Label,Object>> mapDependencies(Filter<Dependency<Label,Label,Object>> f,
                                                           HeadFinder hf,
                                                           String rootName)
Return a set of Label-Label dependencies, represented as Dependency objects, for the Tree. The Labels are the ones of the leaf nodes of the tree, without mucking with them. The head of the sentence is a dependent of a synthetic "root" label.

Parameters:
f - Dependencies are excluded for which the Dependency is not accepted by the Filter
hf - The HeadFinder to use to identify the head of constituents. The code assumes that it can use headPreTerminal(hf) to find a tag and word to make a CyclicCoreLabel.
rootName - Name of the root node.
Returns:
Set of dependencies (each a Dependency between two CyclicCoreLabels, which each contain a tag(), word(), and value(), the last two of which are identical).

yield

public <X extends HasWord> Sentence<X> yield()
Gets the yield of the tree. The Label of all leaf nodes is returned as a list ordered by the natural left to right order of the leaves. Null values, if any, are inserted into the list like any other value.

Returns:
a List of the data in the tree's leaves.

yield

public <X extends HasWord> Sentence<X> yield(Sentence<X> y)
Gets the yield of the tree. The Label of all leaf nodes is returned as a list ordered by the natural left to right order of the leaves. Null values, if any, are inserted into the list like any other value.

Implementation notes: c. 2003: This has been rewritten to thread, so only one List is used. 2007: This method was duplicated to start to give type safety to Sentence. This method will now make a Word for any Leaf which does not itself implement HasWord, and put the Word into the Sentence, so the Sentence elements MUST implement HasWord.

Parameters:
y - The list in which the yield of the tree will be placed. Normally, this will be empty when the routine is called, but if not, the new yield is added to the end of the list.
Returns:
a List of the data in the tree's leaves.

yield

public <T> List<T> yield(List<T> y)
Gets the yield of the tree. The Label of all leaf nodes is returned as a list ordered by the natural left to right order of the leaves. Null values, if any, are inserted into the list like any other value. This has been rewritten to thread, so only one List is used.

Parameters:
y - The list in which the yield of the tree will be placed. Normally, this will be empty when the routine is called, but if not, the new yield is added to the end of the list.
Returns:
a List of the data in the tree's leaves.

taggedYield

public Sentence<TaggedWord> taggedYield()
Gets the tagged yield of the tree. The Label of all leaf nodes is returned as a list ordered by the natural left to right order of the leaves. Null values, if any, are inserted into the list like any other value.

Returns:
a List of the data in the tree's leaves.

labeledYield

public List<LabeledWord> labeledYield()

taggedYield

public <X extends List<TaggedWord>> X taggedYield(X ty)
Gets the tagged yield of the tree -- that is, get the preterminals as well as the terminals. The Label of all leaf nodes is returned as a list ordered by the natural left to right order of the leaves. Null values, if any, are inserted into the list like any other value. This has been rewritten to thread, so only one List is used.

Implementation note: when we summon up enough courage, this method will be changed to take and return a List.

Parameters:
ty - The list in which the tagged yield of the tree will be placed. Normally, this will be empty when the routine is called, but if not, the new yield is added to the end of the list.
Returns:
a List of the data in the tree's leaves.

labeledYield

public List<LabeledWord> labeledYield(List<LabeledWord> ty)

preTerminalYield

public List<Label> preTerminalYield()
Gets the preterminal yield (i.e., tags) of the tree. All data in preleaf nodes is returned as a list ordered by the natural left to right order of the tree. Null values, if any, are inserted into the list like any other value. Pre-leaves are nodes of height 1.

Returns:
a List of the data in the tree's pre-leaves.

preTerminalYield

public List<Label> preTerminalYield(List<Label> y)
Gets the preterminal yield (i.e., tags) of the tree. All data in preleaf nodes is returned as a list ordered by the natural left to right order of the tree. Null values, if any, are inserted into the list like any other value. Pre-leaves are nodes of height 1.

Parameters:
y - The list in which the preterminals of the tree will be placed. Normally, this will be empty when the routine is called, but if not, the new yield is added to the end of the list.
Returns:
a List of the data in the tree's pre-leaves.

getLeaves

public List<Tree> getLeaves()
Gets the leaves of the tree. All leaves nodes are returned as a list ordered by the natural left to right order of the tree. Null values, if any, are inserted into the list like any other value.

Returns:
a List of the leaves.

getLeaves

public List<Tree> getLeaves(List<Tree> list)
Gets the leaves of the tree.

Parameters:
list - The list in which the leaves of the tree will be placed. Normally, this will be empty when the routine is called, but if not, the new yield is added to the end of the list.
Returns:
a List of the leaves.

labels

public Collection<Label> labels()
Get the set of all node and leaf Labels, null or otherwise, contained in the tree.

Specified by:
labels in interface Labeled
Returns:
the Collection (actually, Set) of all values in the tree.

setLabels

public void setLabels(Collection<Label> c)
Description copied from interface: Labeled
Sets the labels associated with this object.

Specified by:
setLabels in interface Labeled
Parameters:
c - The set of Label values

flatten

public Tree flatten()
Return a flattened version of a tree. In many circumstances, this will just return the tree, but if the tree is something like a binarized version of a dependency grammar tree, then it will be flattened back to a dependency grammar tree representation. Formally, a node will be removed from the tree when: it is not a terminal or preterminal, and its label()equal() to the label() of its parent, and all its children will then be promoted to become children of the parent (in the same position in the sequence of daughters.

Returns:
A flattened version of this tree.

flatten

public Tree flatten(TreeFactory tf)
Return a flattened version of a tree. In many circumstances, this will just return the tree, but if the tree is something like a binarized version of a dependency grammar tree, then it will be flattened back to a dependency grammar tree representation. Formally, a node will be removed from the tree when: it is not a terminal or preterminal, and its label()equal() to the label() of its parent, and all its children will then be promoted to become children of the parent (in the same position in the sequence of daughters.

Note: In the current implementation, the tree structure is mainly duplicated, but the links between preterminals and terminals aren't.

Parameters:
tf - TreeFactory used to create tree structure for flattened tree
Returns:
A flattened version of this tree.

subTrees

public Set<Tree> subTrees()
Get the set of all subtrees inside the tree by returning a tree rooted at each node. These are not copies, but all share structure. The tree is regarded as a subtree of itself.

Note: If you only want to form this Set so that you can iterate over it, it is more efficient to simply use the Tree class's own iterator() method. This will iterate over the exact same elements (but perhaps/probably in a different order).

Returns:
the Set of all subtrees in the tree.

subTreeList

public List<Tree> subTreeList()
Get the list of all subtrees inside the tree by returning a tree rooted at each node. These are not copies, but all share structure. The tree is regarded as a subtree of itself.

Note: If you only want to form this Collection so that you can iterate over it, it is more efficient to simply use the Tree class's own iterator() method. This will iterate over the exact same elements (but perhaps/probably in a different order).

Returns:
the List of all subtrees in the tree.

subTrees

public <T extends Collection<Tree>> T subTrees(T n)
Add the set of all subtrees inside a tree (including the tree itself) to the given Collection.

Note: If you only want to form this Collection so that you can iterate over it, it is more efficient to simply use the Tree class's own iterator() method. This will iterate over the exact same elements (but perhaps/probably in a different order).

Parameters:
n - A collection of nodes to which the subtrees will be added.
Returns:
The collection parameter with the subtrees added.

deeperCopy

public Tree deeperCopy()
Same as deepCopy but makes a copy of the labels as well. Uses the TreeFactory of the root node given by treeFactory(). Assumes that your labels give a non-null labelFactory(). (Added by Aria Haghighi.)

Returns:
A deep copy of the tree structure and its labels

deeperCopy

public Tree deeperCopy(TreeFactory tf)
Same as deepCopy but makes a copy of the labels as well. Each Label is copied using the labelFactory() returned by the corresponding node's label. It assumes that your labels give non-null labelFactory. (Added by Aria Haghighi.)

Parameters:
tf - The TreeFactory used to make all nodes in the copied tree structure
Returns:
A Tree that is a deep copy of the tree structure and Labels of the original tree.

deeperCopy

public Tree deeperCopy(TreeFactory tf,
                       LabelFactory lf)
Same as deepCopy but will copy the labels over as well. Each tree is copied with the given TreeFactory. Each Label is copied using the given LabelFactory.

Parameters:
tf - The TreeFactory used to make all nodes in the copied tree structure
lf - The LabelFactory used to make all nodes in the copied tree structure
Returns:
A Tree that is a deep copy of the tree structure and Labels of the original tree.

deepCopy

public Tree deepCopy()
Create a deep copy of the tree. The entire structure is recursively copied, but label data themselves are not cloned. The copy is built using a TreeFactory that will produce a Tree like the input one.

Returns:
a deep structural copy of the tree.

deepCopy

public Tree deepCopy(TreeFactory tf)
Create a deep copy of the tree. The entire structure is recursively copied, but label data themselves are not cloned. By specifying an appropriate TreeFactory, this method can be used to change the type of a Tree.

Parameters:
tf - The TreeFactory to be used for creating the returned Tree
Returns:
a deep structural copy of the tree.

transform

public Tree transform(TreeTransformer transformer)
Create a transformed Tree. The tree is traversed in a depth-first, left-to-right order, and the TreeTransformer is called on each node. It returns some Tree. The transformed tree has a new tree structure (i.e., a "deep copy" is done), but it will usually share its labels with the original tree.

Parameters:
transformer - The function that transforms tree nodes or subtrees
Returns:
a transformation of this Tree

transform

public Tree transform(TreeTransformer transformer,
                      TreeFactory tf)
Create a transformed Tree. The tree is traversed in a depth-first, left-to-right order, and the TreeTransformer is called on each node. It returns some Tree. The transformed tree has a new tree structure (i.e., a "deep copy" is done), but it will usually share its labels with the original tree.

Parameters:
transformer - The function that transforms tree nodes or subtrees
tf - The TreeFactory which will be used for creating new nodes for the returned Tree
Returns:
a transformation of this Tree

spliceOut

public Tree spliceOut(Filter<Tree> nodeFilter)
Creates a (partial) deep copy of the tree, where all nodes that the filter does not accept are spliced out. If the result is not a tree (that is, it's a forest), an empty root node is generated.

Parameters:
nodeFilter - a Filter method which returns true to mean keep this node, false to mean delete it
Returns:
a filtered copy of the tree

spliceOut

public Tree spliceOut(Filter<Tree> nodeFilter,
                      TreeFactory tf)
Creates a (partial) deep copy of the tree, where all nodes that the filter does not accept are spliced out. That is, the particular modes for which the Filter returns false are removed from the Tree, but those nodes' children are kept (assuming they pass the Filter, and they are added in the appropriate left-to-right ordering as new children of the parent node. If the root node is deleted, so that the result would not be a tree (that is, it's a forest), an empty root node is generated. If nothing is accepted, null is returned.

Parameters:
nodeFilter - a Filter method which returns true to mean keep this node, false to mean delete it
tf - A TreeFactory for making new trees. Used if the root node is deleted.
Returns:
a filtered copy of the tree.

prune

public Tree prune(Filter<Tree> filter)
Creates a deep copy of the tree, where all nodes that the filter does not accept and all children of such nodes are pruned. If all ' of a node's children are pruned, that node is cut as well. A Filter can assume that it will not be called with a null argument.

For example, the following code excises all PP nodes from a Tree: Filter f = new Filter { public boolean accept(Tree t) { return ! t.label().value().equals("PP"); } } tree.prune(f);

Parameters:
filter - the filter to be apply
Returns:
a filtered copy of the tree.

prune

public Tree prune(Filter<Tree> filter,
                  TreeFactory tf)
Creates a deep copy of the tree, where all nodes that the filter does not accept and all children of such nodes are pruned. If all of a node's children are pruned, that node is cut as well. A Filter can assume that it will not be called with a null argument.

Parameters:
filter - the filter to be apply
tf - the TreeFactory to be used to make new Tree nodes if needed
Returns:
a filtered copy of the tree, including the possibility of null if the root node of the tree is filtered

skipRoot

public Tree skipRoot()
Returns first child if it is single and if the label at the current node is either "ROOT" or empty.


treeFactory

public abstract TreeFactory treeFactory()
Return a TreeFactory that produces trees of the appropriate type.

Returns:
A factory to produce Trees

parent

public Tree parent()
Return the parent of the tree node. This routine may return null meaning simply that the implementation doesn't know how to determine the parent node, rather than there is no such node.

Returns:
The parent Tree node or null
See Also:
parent(Tree)

parent

public Tree parent(Tree root)
Return the parent of the tree node. This routine will traverse a tree (depth first) from the given root, and will correctly find the parent, regardless of whether the concrete class stores parents. It will only return null if this node is the root node, or if this node is not contained within the tree rooted at root.

Parameters:
root - The root node of the whole Tree
Returns:
the parent Tree node if any; else null

size

public int size()
Returns the number of nodes the tree contains. This method implements the size() function required by the Collections interface. The size of the tree is the number of nodes it contains (of all types, including the leaf nodes and the root).

Specified by:
size in interface Collection<Tree>
Specified by:
size in class AbstractCollection<Tree>
Returns:
The size of the tree
See Also:
depth()

ancestor

public Tree ancestor(int height,
                     Tree root)
Return the ancestor tree node height nodes up from the current node.

Parameters:
height - How many nodes up to go. A parameter of 0 means return this node, 1 means to return the parent node and so on.
root - The root node that this Tree is embedded under
Returns:
The ancestor at height height. It returns null if it does not exist or the tree implementation does not keep track of parents

iterator

public Iterator<Tree> iterator()
Returns an iterator over all the nodes of the tree. This method implements the iterator() method required by the Collections interface. It does a preorder (children after node) traversal of the tree. (A possible extension to the class at some point would be to allow different traversal orderings via variant iterators.)

Specified by:
iterator in interface Iterable<Tree>
Specified by:
iterator in interface Collection<Tree>
Specified by:
iterator in class AbstractCollection<Tree>
Returns:
An interator over the nodes of the tree

postOrderNodeList

public List<Tree> postOrderNodeList()

preOrderNodeList

public List<Tree> preOrderNodeList()

valueOf

public static Tree valueOf(String str)
                    throws IOException
This gives you a tree from a String representation (as a bracketed Tree, of the kind produced by toString(), pennPrint(), or as in the Penn Treebank). It's not the most efficient thing to do for heavy duty usage. The Tree returned is created by a StringLabeledScoredTreeReaderFactory.

Parameters:
str - The tree as a bracketed list in a String.
Returns:
The Tree
Throws:
IOException - If Tree format is not valid

valueOf

public static Tree valueOf(String str,
                           TreeReaderFactory trf)
                    throws IOException
This gives you a tree from a String representation (as a bracketed Tree, of the kind produced by toString(), pennPrint(), or as in the Penn Treebank. It's not the most efficient thing to do for heavy duty usage.

Parameters:
str - The tree as a bracketed list in a String.
trf - The TreeFactory used to make the new Tree
Returns:
The Tree
Throws:
IOException - If Tree format is not valid

getChild

public Tree getChild(int i)
Return the child at some daughter index. The children are numbered starting with an index of 0.

Parameters:
i - The daughter index
Returns:
The tree at that daughter index

removeChild

public Tree removeChild(int i)
Destructively removes the child at some daughter index and returns it. Note that this method will throw an ArrayIndexOutOfBoundsException if the daughter index is too big for the list of daughters.

Parameters:
i - The daughter index
Returns:
The tree at that daughter index

addChild

public void addChild(int i,
                     Tree t)
Adds the tree t at the index position among the daughters. Note that this method will throw an ArrayIndexOutOfBoundsException if the the daughter index is too big for the list of daughters.

Parameters:
i - the index position at which to add the new daughter
t - the new daughter

addChild

public void addChild(Tree t)
Adds the tree t at the last index position among the daughters.

Parameters:
t - the new daughter

setChild

public Tree setChild(int i,
                     Tree t)
Replaces the ith child of this with the tree t. Note that this method will throw an ArrayIndexOutOfBoundsException if the child index is too big for the list of children.

Parameters:
i - The index position at which to replace the child
t - The new child
Returns:
The tree that was previously the ith d

dominates

public boolean dominates(Tree t)
Returns true if this dominates the Tree passed in as an argument. Object equality (==) rather than .equals() is used to determine domination. t.dominates(t) returns false.


dominationPath

public List<Tree> dominationPath(Tree t)
Returns the path of nodes leading down to a dominated node, including this and the dominated node itself. Returns null if t is not dominated by this. Object equality (==) is the relevant criterion. t.dominationPath(t) returns null.


pathNodeToNode

public List<Tree> pathNodeToNode(Tree t1,
                                 Tree t2)
Given nodes t1 and t2 which are dominated by this node, returns a list of all the nodes on the path from t1 to t2, inclusive, or null if none found.


joinNode

public Tree joinNode(Tree t1,
                     Tree t2)
Given nodes t1 and t2 which are dominated by this node, returns their "join node": the node j such that j dominates both t1 and t2, and every other node which dominates both t1 and t2 dominates j. In the special case that t1 dominates t2, return t1, and vice versa. Return null if no such node can be found.


cCommands

public boolean cCommands(Tree t1,
                         Tree t2)
Given nodes t1 and t2 which are dominated by this node, returns true iff t1 c-commands t2. (A node c-commands its sister(s) and any nodes below its sister(s).)


siblings

public List<Tree> siblings(Tree root)
Returns the siblings of this Tree node. The siblings are all children of the parent of this node except this node.

Parameters:
root - The root within which this tree node is contained
Returns:
The siblings as a list, an empty list if there are no siblings. The returned list is a modifiable new list structure, but contains the actual children.

insertDtr

public void insertDtr(Tree dtr,
                      int position)
insert dtr after position existing daughters in this.


value

public String value()
Description copied from interface: Label
Return a String representation of just the "main" value of this label.

Specified by:
value in interface Label
Returns:
the "value" of the label

setValue

public void setValue(String value)
Description copied from interface: Label
Set the value for the label (if one is stored).

Specified by:
setValue in interface Label
Parameters:
value - - the value for the label

setFromString

public void setFromString(String labelStr)
Description copied from interface: Label
Set the contents of this label to this String representing the complete contents of the label. A class implementing label may throw an UnsupportedOperationException for this method (only). Typically, this method would do some appropriate decoding of the string in a way that sets multiple fields in an inverse of the toString() method.

Specified by:
setFromString in interface Label
Parameters:
labelStr - the String that translates into the content of the label

labelFactory

public LabelFactory labelFactory()
Returns a factory that makes labels of the same type as this one. May return null if no appropriate factory is known.

Specified by:
labelFactory in interface Label
Returns:
the LabelFactory for this kind of label

leftCharEdge

public int leftCharEdge(Tree node)
Returns the positional index of the left edge of node within the tree, as measured by characters. Returns -1 if node is not found.


rightCharEdge

public int rightCharEdge(Tree node)
Returns the positional index of the right edge of node within the tree, as measured by characters. Returns -1 if node is not found. rightCharEdge returns the index of the rightmost character + 1, so that rightCharEdge(getLeaves().get(i)) == leftCharEdge(getLeaves().get(i+1))

Parameters:
node - The subtree to look for in this Tree
Returns:
The positional index of the right edge of node

nodeNumber

public int nodeNumber(Tree root)
Calculates the node's number, defined as the number of nodes traversed in a left-to-right, depth-first search of the tree starting at root and ending at this. Returns -1 if root does not contain this.

Parameters:
root - the root node of the relevant tree
Returns:
the number of the current node, or -1 if root does not contain this.

getNodeNumber

public Tree getNodeNumber(int i)
Fetches the ith node in the tree, with node numbers defined as in nodeNumber(Tree).

Parameters:
i - the node number to fetch
Returns:
the ith node in the tree
Throws:
IndexOutOfBoundsException - if i is not between 1 and the number of nodes (inclusive) contained in this.

indexLeaves

public void indexLeaves()
Assign sequential integer indices to the leaves of the tree rooted at this Tree, starting with 1. The leaves are traversed from left to right. If the node is already indexed, then it uses the existing index. This will only work if the leaves extend CoreMap.


indexSpans

public void indexSpans(int startIndex)

indexSpans

public Pair<Integer,Integer> indexSpans(MutableInteger startIndex)
Assigns span indices (BeginIndexAnnotation and EndIndexAnnotation) to all nodes in a tree. The beginning index is equivalent to the IndexAnnotation of the first leaf in the constituent. The end index is equivalent to the first integer after the IndexAnnotation of the last leaf in the constituent.

Parameters:
startIndex - Begin indexing at this value


Stanford NLP Group