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Does anyone have a good tool for drawing parse trees arising from a context-free grammar? There is this question, but it dealt specifically with finite automata instead of parse trees. I've been using graphviz, but it's kind of annoying to have to label each node individually etc.

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  • Are you trying to visualize the parse tree of a parser's output, or the parser itself? Commented Feb 11, 2011 at 18:19
  • @Flynn1179: the output. But I don't want to write a parser, I want something that is like paint, i.e. I just draw some trees. Commented Feb 11, 2011 at 18:27
  • 1
    Moved to software recommendations SE: Tool for drawing parse trees Commented Apr 17, 2020 at 17:36

3 Answers 3

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You can use http://ironcreek.net/phpsyntaxtree/.

Example:

enter image description here

Input was:

[ROOT
  [S
    [S
      [NP [PRP It]]
      [VP [VBZ is]
        [NP
          [QP [RB nearly] [DT half] [JJ past] [CD five]]]]]
    [, ,]
    [S
      [NP [PRP we]]
      [VP [MD can] [RB not]
        [VP [VB reach]
          [NP [NN town]]
          [PP [IN before]
            [NP [NN dark]]]]]]
    [, ,]
    [S
      [NP [PRP we]]
      [VP [MD will]
        [VP [VB miss]
          [NP [NN dinner]]]]]
    [. .]]]

Also works if the string has no line breaks, e.g.:

[S [NP [DT The] [NN man]] [VP [VBZ is] [VP [VBG running] [PP [IN on] [NP [DT the] [NN mountain]]]]] [. .]]
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2

If you have a well-written context-free grammar(CFG) then you can draw the tree diagram simply by using nltk library.

import nltk
#defining Contex Free Grammar
grammar = nltk.CFG.fromstring("""
  S  -> NP VP
  NP -> Det Nom | PropN
  Nom -> Adj Nom | N
  VP -> V Adj | V NP | V S | V NP PP
  PP -> P NP
  PropN -> 'Buster' | 'Chatterer' | 'Joe'
  Det -> 'the' | 'a'
  N -> 'bear' | 'squirrel' | 'tree' | 'fish' | 'log'
  Adj  -> 'angry' | 'frightened' |  'little' | 'tall'
  V ->  'chased'  | 'saw' | 'said' | 'thought' | 'was' | 'put'
  P -> 'on'
  """)

sentence = 'the angry bear chased the frightened little squirrel'.split()
def parse(sent):
    #Returns nltk.Tree.Tree format output
    a = []  
    parser = nltk.ChartParser(grammar)
    for tree in parser.parse(sent):
        a.append(tree)
    return(a[0]) 

#Gives output as structured tree   
print(parse(sentence))

#Gives tree diagrem in tkinter window
parse(sentence).draw()

Structured tree output

Tree Diagram in Tkinter Window

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2

http://brenocon.com/parseviz/:

Input:

(S (NP (DT The) (NN man)) (VP (VBZ is) (VP (VBG running) (PP (IN on) (NP (DT the) (NN mountain))))) (. .))

Output:

enter image description here

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