nltk.tree.AbstractParentedTree

class documentation

class AbstractParentedTree(Tree): (source)

Known subclasses: nltk.tree.MultiParentedTree, nltk.tree.ParentedTree

Constructor: AbstractParentedTree(node, children)

An abstract base class for a Tree that automatically maintains pointers to parent nodes. These parent pointers are updated whenever any change is made to a tree's structure. Two subclasses are currently defined:

ParentedTree is used for tree structures where each subtree has at most one parent. This class should be used in cases where there is no"sharing" of subtrees.

MultiParentedTree is used for tree structures where a subtree may have zero or more parents. This class should be used in cases where subtrees may be shared.

Subclassing

The AbstractParentedTree class redefines all operations that modify a tree's structure to call two methods, which are used by subclasses to update parent information:

_setparent() is called whenever a new child is added.

_delparent() is called whenever a child is removed.

Method	`__delitem__`	Undocumented
Method	`__delslice__`	Undocumented
Method	`__getslice__`	Undocumented
Method	`__init__`	Undocumented
Method	`__setitem__`	Undocumented
Method	`__setslice__`	Undocumented
Method	`append`	Undocumented
Method	`extend`	Undocumented
Method	`insert`	Undocumented
Method	`pop`	Undocumented
Method	`remove`	Undocumented
Method	`_delparent`	Update the parent pointer of `child` to not point to self. This method is only called if the type of `child` is `Tree`; i.e., it is not called when removing a leaf from a tree. This method is always called before the child is actually removed from the child list of ...
Method	`_setparent`	Update the parent pointer of `child` to point to `self`. This method is only called if the type of `child` is `Tree`; i.e., it is not called when adding a leaf to a tree. This method is always called before the child is actually added to the child list of ...

Inherited from Tree:

Class Method	`convert`	Convert a tree between different subtypes of Tree. `cls` determines which class will be used to encode the new tree.
Class Method	`fromlist`	Convert nested lists to a NLTK Tree
Class Method	`fromstring`	Read a bracketed tree string and return the resulting tree. Trees are represented as nested brackettings, such as:
Method	`__add__`	Undocumented
Method	`__copy__`	Undocumented
Method	`__deepcopy__`	Undocumented
Method	`__eq__`	Undocumented
Method	`__getitem__`	Undocumented
Method	`__lt__`	Undocumented
Method	`__mul__`	Undocumented
Method	`__radd__`	Undocumented
Method	`__repr__`	Undocumented
Method	`__rmul__`	Undocumented
Method	`__str__`	Undocumented
Method	`chomsky_normal_form`	This method can modify a tree in three ways:
Method	`collapse_unary`	Collapse subtrees with a single child (ie. unary productions) into a new non-terminal (Tree node) joined by 'joinChar'. This is useful when working with algorithms that do not allow unary productions, and completely removing the unary productions would require loss of useful information...
Method	`copy`	Undocumented
Method	`draw`	Open a new window containing a graphical diagram of this tree.
Method	`flatten`	Return a flat version of the tree, with all non-root non-terminals removed.
Method	`freeze`	Undocumented
Method	`height`	Return the height of the tree.
Method	`label`	Return the node label of the tree.
Method	`leaf_treeposition`	No summary
Method	`leaves`	Return the leaves of the tree.
Method	`pformat`	No summary
Method	`pformat_latex_qtree`	Returns a representation of the tree compatible with the LaTeX qtree package. This consists of the string `\Tree` followed by the tree represented in bracketed notation.
Method	`pos`	Return a sequence of pos-tagged words extracted from the tree.
Method	`pprint`	Print a string representation of this Tree to 'stream'
Method	`pretty_print`	Pretty-print this tree as ASCII or Unicode art. For explanation of the arguments, see the documentation for `nltk.treeprettyprinter.TreePrettyPrinter`.
Method	`productions`	Generate the productions that correspond to the non-terminal nodes of the tree. For each subtree of the form (P: C1 C2 ... Cn) this produces a production of the form P -> C1 C2 ... Cn.
Method	`set_label`	Set the node label of the tree.
Method	`subtrees`	Generate all the subtrees of this tree, optionally restricted to trees matching the filter function.
Method	`treeposition_spanning_leaves`	No summary
Method	`treepositions`	No summary
Method	`un_chomsky_normal_form`	This method modifies the tree in three ways:
Class Variable	`__ge__`	Undocumented
Class Variable	`__gt__`	Undocumented
Class Variable	`__le__`	Undocumented
Class Variable	`__ne__`	Undocumented
Class Variable	`node`	Undocumented
Class Method	`_parse_error`	Display a friendly error message when parsing a tree string fails. :param s: The string we're parsing. :param match: regexp match of the problem token. :param expecting: what we expected to see instead.
Method	`_frozen_class`	Undocumented
Method	`_get_node`	Outdated method to access the node value; use the label() method instead.
Method	`_pformat_flat`	Undocumented
Method	`_repr_png_`	Draws and outputs in PNG for ipython. PNG is used instead of PDF, since it can be displayed in the qt console and has wider browser support.
Method	`_set_node`	Outdated method to set the node value; use the set_label() method instead.
Instance Variable	`_label`	Undocumented

def __delitem__(self, index): (source) ¶

overrides nltk.tree.Tree.__delitem__

Undocumented

def __delslice__(self, start, stop): (source) ¶

Undocumented

def __getslice__(self, start, stop): (source) ¶

Undocumented

def __init__(self, node, children=None): (source) ¶

overrides nltk.tree.Tree.__init__

overridden in nltk.tree.MultiParentedTree, nltk.tree.ParentedTree

Undocumented

def __setitem__(self, index, value): (source) ¶

overrides nltk.tree.Tree.__setitem__

Undocumented

def __setslice__(self, start, stop, value): (source) ¶

Undocumented

def append(self, child): (source) ¶

Undocumented

def extend(self, children): (source) ¶

Undocumented

def insert(self, index, child): (source) ¶

Undocumented

def pop(self, index=-1): (source) ¶

Undocumented

def remove(self, child): (source) ¶

Undocumented

@abstractmethod
def _delparent(self, child, index): (source) ¶

overridden in nltk.tree.MultiParentedTree, nltk.tree.ParentedTree

Update the parent pointer of child to not point to self. This method is only called if the type of child is Tree; i.e., it is not called when removing a leaf from a tree. This method is always called before the child is actually removed from the child list of self.

Parameters
child:Tree	Undocumented
index:int	The index of `child` in `self`.

@abstractmethod
def _setparent(self, child, index, dry_run=False): (source) ¶

overridden in nltk.tree.MultiParentedTree, nltk.tree.ParentedTree

Update the parent pointer of child to point to self. This method is only called if the type of child is Tree; i.e., it is not called when adding a leaf to a tree. This method is always called before the child is actually added to the child list of self.

Parameters
child:Tree	Undocumented
index:int	The index of `child` in `self`.
dry_run	If true, the don't actually set the child's parent pointer; just check for any error conditions, and raise an exception if one is found.
Raises
`TypeError`	If `child` is a tree with an impropriate type. Typically, if `child` is a tree, then its type needs to match the type of `self`. This prevents mixing of different tree types (single-parented, multi-parented, and non-parented).