Package nltk :: Module tree :: Class AbstractParentedTree

type AbstractParentedTree

object --+        
         |        
      list --+    
             |    
          Tree --+
                 |
                AbstractParentedTree

Known Subclasses:

An abstract base class for Trees that automatically maintain pointers to their parents. 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.

Instance Methods

[hide private]

new list

__init__(self, node_or_str, children=None)
Construct a new tree.

source code

_setparent(self, child, index, dry_run=False)
Update child's parent pointer to point to self. source code

_delparent(self, child, index)
Update child's parent pointer to not point to self. source code

__delitem__(self, index)
del x[y]

source code

__setitem__(self, index, value)
x[i]=y

source code

append(self, child)
append object to end

source code

extend(self, children)
extend list by appending elements from the iterable

source code

insert(self, index, child)
insert object before index

source code

item

pop(self, index=-1)
remove and return item at index (default last)

source code

remove(self, child)
remove first occurrence of value

source code

__getslice__(self, start, stop)
x[i:j]

source code

__delslice__(self, start, stop)
del x[i:j]

source code

__setslice__(self, start, stop, value)
x[i:j]=y

source code

Inherited from Tree: __add__, __eq__, __ge__, __getitem__, __gt__, __le__, __lt__, __mul__, __ne__, __radd__, __repr__, __rmul__, __str__, chomsky_normal_form, collapse_unary, copy, draw, flatten, freeze, height, leaf_treeposition, leaves, pos, pprint, pprint_latex_qtree, productions, subtrees, treeposition_spanning_leaves, treepositions, un_chomsky_normal_form

Inherited from Tree (private): _frozen_class, _pprint_flat

Inherited from list: __contains__, __getattribute__, __hash__, __iadd__, __imul__, __iter__, __len__, __reversed__, count, index, reverse, sort

Class Methods

[hide private]

Inherited from Tree: convert, parse

Inherited from Tree (private): _parse_error

Static Methods

[hide private]

Inherited from Tree: __new__

Method Details

[hide private]

init(self, node_or_str, children=None)
(Constructor)

source code

Construct a new tree. This constructor can be called in one of two ways:

Tree(node, children) constructs a new tree with the specified node value and list of children.
Tree(s) constructs a new tree by parsing the string s. It is equivalent to calling the class method Tree.parse(s).

Returns: new list
Overrides: list.__init__: (inherited documentation)

_setparent(self, child, index, dry_run=False)

source code

Update child's parent pointer to point to self. This method is only called if child's type 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 self's child list.

Parameters:

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.
child (Tree)

Raises:

TypeError - If child is a tree with an impropriate type. Typically, if child is a tree, then its type needs to match self's type. This prevents mixing of different tree types (single-parented, multi-parented, and non-parented).

_delparent(self, child, index)

source code

Update child's parent pointer to not point to self. This method is only called if child's type 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 self's child list.

Parameters:

index (int) - The index of child in self.
child (Tree)

delitem(self, index)
(Index deletion operator)

source code

del x[y]

Overrides: list.__delitem__: (inherited documentation)

setitem(self, index, value)
(Index assignment operator)

source code

x[i]=y

Overrides: list.__setitem__: (inherited documentation)

append(self, child)

source code

append object to end

Overrides: list.append: (inherited documentation)

extend(self, children)

source code

extend list by appending elements from the iterable

Overrides: list.extend: (inherited documentation)

insert(self, index, child)

source code

insert object before index

Overrides: list.insert: (inherited documentation)

pop(self, index=-1)

source code

remove and return item at index (default last)

Returns: item
Overrides: list.pop: (inherited documentation)

remove(self, child)

source code

remove first occurrence of value

Overrides: list.remove: (inherited documentation)

getslice(self, start, stop)
(Slicling operator)

source code

x[i:j]

Use of negative indices is not supported.

Overrides: list.__getslice__: (inherited documentation)

delslice(self, start, stop)
(Slice deletion operator)

source code

del x[i:j]

Use of negative indices is not supported.

Overrides: list.__delslice__: (inherited documentation)

setslice(self, start, stop, value)
(Slice assignment operator)

source code

x[i:j]=y

Use of negative indices is not supported.

Overrides: list.__setslice__: (inherited documentation)

type AbstractParentedTree

Subclassing

__init__(self, node_or_str, children=None) (Constructor)

_setparent(self, child, index, dry_run=False)

_delparent(self, child, index)

__delitem__(self, index) (Index deletion operator)

__setitem__(self, index, value) (Index assignment operator)

append(self, child)

extend(self, children)

insert(self, index, child)

pop(self, index=-1)

remove(self, child)

__getslice__(self, start, stop) (Slicling operator)

__delslice__(self, start, stop) (Slice deletion operator)

__setslice__(self, start, stop, value) (Slice assignment operator)

init(self, node_or_str, children=None)
(Constructor)

delitem(self, index)
(Index deletion operator)

setitem(self, index, value)
(Index assignment operator)

getslice(self, start, stop)
(Slicling operator)

delslice(self, start, stop)
(Slice deletion operator)

setslice(self, start, stop, value)
(Slice assignment operator)