Package Summary

stanford_parser_ros wraps the parse tree and dependency functionality of the Stanford Parser and Stanford Dependencies Parser (with parse tree and dependencies outputs) for ROS. It receives a string (a command sentence) and returns a Parse, which consists of a flattened parse tree and a list of dependencies (such as direct object, indirect object, etc.).

Author: Brian Thomas
License: BSD
Source: hg https://kforge.ros.org/appmanandroid/roboframenet (branch: None)

WARNING: This documentation refers to an outdated version of rosjava and is probably incorrect. Use at your own risk.

Contents

Interpreting Output Messages
1. Parse tree
2. Dependencies

Interpreting Output Messages

Parse tree

A python utility is provided to unsquash the parse trees and dependencies output by stanford_parser_ros. This will create a tree structure:

from stanford_parser_msgs import unsquash_tree

[...]

def callback(msg): # msg type: stanford_parser_msgs/Parse
  [...]
  parse_tree = unsquash_tree(msg)
  [...]

Each node in the tree -- an instance of the class Tree -- has the following elements:

node.tag        # string
node.score      # double -- confidence rating of the Stanford Parser
node.word       # string
node.word_index # integer -- node.word = msg.words[node.word_index]
node.children   # listof(Tree)

The part-of-speech tags used in the Stanford Parser come from Penn Treebank II and can be found here.

Dependencies

Dependencies (a list located under msg.dependencies) have the following 3 elements:

relation: Relation between the governor and dependent. A complete set of relations can be found in the Stanford Dependencies Manual.
governor_index: The index of the governor in msg.words. In other words, the governor is msg.words[dependency.governor_index].
dependent_index: The index of the dependent in msg.words. In other words, the dependent is msg.words[dependency.dependent_index].

For instance, the sentence "Give Bill the ball." has, among others, the dependency "dobj(give-2, ball-5)". For this dependency, relation is "dobj", governor_index is 2, and dependent_index is 5.