edu.stanford.nlp.trees.tregexby Roger Levy.
Tsurgeon provides a way of editing trees based on a set of operations that are applied to tree locations matching a tregex pattern.
This exception is thrown when parse errors are encountered.
A runtime exception that indicates something went wrong parsing a Tsurgeon expression.
A package for performing
transformations of trees to be used in conjunction with
edu.stanford.nlp.trees.tregex by Roger Levy.
Look at the description below and the class comments for
Tsurgeon for more information.
Operations are applied while their pattern match. You must be careful to ensure that patterns do not continue to match after they have been applied, or else Tsurgeon will go into an infinite loop.
delete name_1 name_2 ... name_m For each name_i, deletes the node it names and everything below it. prune name_1 name_2 ... name_m For each name_i, prunes out the node it names. Pruning differs from deletion in that if pruning a node causes its parent to have no children, then the parent is in turn pruned too. excise name1 name2 The name1 node should either dominate or be the same as the name2 node. This excises out everything from name1 to name2. All the children of name2 go into the parent of name1, where name1 was. relabel name new-label Relabels the node to have the new label. There are three possible forms for the new-label: relabel nodeX VP - for changing a node label to an alphanumeric string, relabel nodeX /''/ - for relabeling a node to something that isn't a valid identifier without quoting, and relabel nodeX /^VB(.*)$/verb\/$1/ - for regular expression based relabeling. In the last case, all matches of the regular expression against the node label are replaced with the replacement String. This has the semantics of Java/Perl's replaceAll: you may use capturing groups and put them in replacements with $n. Also, as in the example, you can escape a slash in the middle of the second and third forms with \/ and \\. This last version lets you make a new label that is an arbitrary String function of the original label and additional characters that you supply. relabel name new-label Renames the node to have the new label. If the new-label is not a valid tregex identifier, you can quote it by surrounding it by pipe characters (|new-label|). relabel name regex groupNumber matches the regex against the node's current label, and then renames the node to have a label that corresponds to the n-th group of the regex. insert name position insert tree position inserts the named node, or a manually specified tree (see below for syntax), into the position specified. Right now the only ways to specify position are: $+ name to insert the left sister of the named node $- name to insert the right sister of the named node >i name the i_th daughter of the named node. >-i name the i_th daughter, counting from the right, of the named node. move name position moves the named node into the specified position. To be precise, it deletes (*NOT* prunes) the node from the tree, and re-inserts it into the specified position. replace name1 name2 deletes name1 and inserts a copy of name2 in its place. adjoin tree target-node adjoins the specified auxiliary tree (see below for syntax) into the target node specified. The daughters of the target node will become the daughters of the foot of the auxiliary tree. adjoinH tree target-node similar to adjoin, but preserves the target node and makes it the root of tree adjoinF tree target-node similar to adjoin, but preserves the target node and makes it the foot of tree. It thus retains its status as parent of its children, placed in the appropriate spot in tree. coindex name_1 name_2 ... name_m Puts a (Penn Treebank style) coindexation suffix of the form "-N" on each of nodes name_1 through name_m. The value of N will be automatically generated in reference to the existing coindexations in the tree, so that there is never an accidental clash of indices across things that are not meant to be coindexed.
For all lines after the first line of the file, the character % introduces a comment that extends to the end of the line. All other intended uses of % must be escaped as \% .
A tree to be adjoined in can be specified with LISP-like parenthetical-bracketing tree syntax such as those used for the Penn Treebank. For example, for the NP "the dog" to be inserted you might use the syntax:
(NP (Det the) (N dog))
That's all that there is for a tree to be inserted. Auxiliary trees (a la Tree Adjoining Grammar) must also have exactly one frontier node ending in the character "@", which marks it as the "foot" node for adjunction. Final instances of the character "@" in terminal node labels will be removed from the actual label of the tree.
For example, if you wanted to adjoin the adverb "breathlessly" into a VP, you might specify the following auxiliary tree:
(VP (Adv breathlessly) VP@ )
All other instances of "@" in terminal nodes must be escaped (i.e., appear as \@); this escaping will be removed by tsurgeon.
In addition, any node of a tree can be named (the same way as in tregex), by appending =name to the node label. That name can be referred to by subsequent tsurgeon operations triggered by the same match. All other instances of "=" in node labels must be escaped (i.e., appear as \=); this escaping will be removed by tsurgeon. For example, if you want to insert an NP trace somewhere and coindex it with a node named "antecedent" you might say
insert (NP (-NONE- *T*=trace)) node-location coindex trace antecedent $
TO DO: Fix the relabel operation to allow any node label without || syntax. Document adjoinH and adjoinF. Provide a spliceIn(Above) operation that lets you insert a node above a given node.
Stanford NLP Group