3

I would like to get the parent and child nodes of a node in an nltk tree. I have seen this answer here but I couldn't manage to fit it to my purposes.

For example, having this tree:

        ROOT              
         |                 
         S                
  _______|______________   
 |       VP             | 
 |    ___|____          |  
 NP  |       ADJP       | 
 |   |    ____|____     |  
PRP VBZ  RB        JJ   . 
 |   |   |         |    |  
 It  is  so       nice  .

I have this code taken and modified from other answers that gives some information but is not quite what I want.

ptree = ParentedTree.fromstring('(ROOT (S (NP (PRP It)) \
    (VP (VBZ is) (ADJP (RB so) (JJ nice))) (. .)))')

leaf_values = ptree.leaves()

ptree.pretty_print()

if 'nice' in leaf_values:
    leaf_index = leaf_values.index('nice')
    print(leaf_index)
    tree_location = ptree.leaf_treeposition(leaf_index)
    print(tree_location)
    print(ptree[tree_location])
    print(tree_location[:-1])
    print(ptree[tree_location[:-1]])
    print(tree_location[:-2])
    print(ptree[tree_location[:-2]])

3
(0, 1, 1, 1, 0)
nice
(0, 1, 1, 1)
(JJ nice)
(0, 1, 1)
(ADJP (RB so) (JJ nice))

I would like to implement something like the following. Assume I have the position/node 'nice'. I would like to make a function so that I get the position of 'JJ' when I enter the position of 'nice' as a parameter. Like get_parent(positionOf('nice')) returns positionOf('JJ'). And then I can do get_parent(positionOf('JJ')) and it returns positionOf('ADJP'), etc.

I would also like to get the childs of a node, for example, if I have get_childs(positionOf('ADJP')) it should return position('RB') and positionOf('JJ').

Does someone know how could I implement that? Could you provide a small example?

Community
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jto
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1 Answers1

2

The parent of the leaf: print(ptree[tree_location[:-1]].label())

The first ancestor: print(ptree[tree_location[:-2]].label())

Hager Hosny
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