Extract a path of dependency relations from the ROOT to a token? SPACY

Question

Extract a path of dependency relations from the ROOT to a token? SPACY. The code I have it extract the whole path

import spacy

sentence = "I saw the man with a telescop"

nlp = spacy.load('en')
doc = nlp(sentence)

for sent in doc.sents:
    for token in sent:
        print("{}\t{}\t{}\t{}".format(token.i, token.text, token.head, token.dep_))

Answer 1

The dependency tree is basically a graph, so if you want to find the (shortest) path to ROOT, you need to use some graph-based libraries like networkx. Let's say you want to extract a path from a token "telescop" to the root. Then you could try to do something like this:

import spacy
import networkx

sentence = "I saw the man with a telescop"

nlp = spacy.load('en_core_web_sm')
doc = nlp(sentence)
edges = []

for sent in doc.sents:
    for token in sent:
        print("{}\t{}\t{}\t{}".format(token.i, token.text, token.head, token.dep_))
        if token.dep_ == "ROOT":
            target = token.text
        for child in token.children:
            edges.append(("{0}".format(token.lower_), "{0}".format(child.lower_)))


graph = networkx.Graph(edges)
print(nx.shortest_path(graph, source="telescop", target=target))

Result:

0   I   saw nsubj
1   saw saw ROOT
2   the man det
3   man saw dobj
4   with    saw prep
5   a   telescop    det
6   telescop    with    pobj
['telescop', 'with', 'saw']